Why does my computer keep disappearing from the local network?

In article , Eric Stevens
wrote:

Now that I can access the router, what should I be looking for?

the router is not the problem.

Eric Stevens wrote:
On Tue, 16 Jul 2019 22:00:28 +1200, Eric Stevens
wrote:

On Tue, 16 Jul 2019 17:34:47 +1200, Eric Stevens
wrote:

I've tried entering the Router to see how it is presently configure
but it is not presently responding to my attempts get in with
192.168.20.1. I will reset things and try again later.
That referred to trying to access the router from Corsair. I've since
tried to contact it from Dell, with no more luck. Everything I've read
says that 192.168.1.1 is the correct address.

I should have written "Everything I've read says that 192.168.20.1 is
the correct address." My copy of the manual says that in six places.
In fact 192.168.1.1 is the correct address and now that I have used
that I can get in.

Now that I can access the router, what should I be looking for?

I can't remembere quite what I did when I received the router: it was
sent to me by Internet provider to replace an earlier less than
satisfactory router. I may have just plugged it in and set it running.
Unlike my earlier router my IP can deal with problems from their end
of the line. Could they have configured it so that I couldn't get at
it from my end? It seems unlikely but I will print and read the manual
and may be talk to their help desk. No doubt more tomorrow.

When you ran an nbtscan.exe scan, did all
the machines you expected to see, show up ?
You can try this from any machine, and see
if the other machines respond. (If would
help if your APIPA machine got its mojo back.)

http://www.unixwiz.net/tools/nbtscan.html

If you try pinging from machine to machine,
does ping work for every machine-combo ?
This is a test that the topology of your
network, is what you think it is. For example,
I have two subnets which use private addresses,
and you cannot expect the router to "join them
together" in a useful way. so I cannot ping
something on the (isolated) segment. I have to
take the network apart and jack into it separately
to work on it.

With regard to your router, you check the DHCP
starting address and number of nodes, to see
if there is sufficient address space for everything.
I might aim for double the number of addresses,
just to make sure. If I had 10 machines, I'd want
the DHCP server to have 20 addresses, just in case.
There's no particular reason to set that to 253
either. A carefully sculpted number, helps when
you're debugging things.

I have one router that lists everything that
got a DHCP address. And another router that
can't be bothered to show such info.

Paul

On Wed, 17 Jul 2019 00:56:04 -0400, Paul wrote:

If you try pinging from machine to machine,
does ping work for every machine-combo ?
This is a test that the topology of your
network, is what you think it is.

For example,
I have two subnets which use private addresses,
and you cannot expect the router to "join them
together" in a useful way. so I cannot ping
something on the (isolated) segment. I have to
take the network apart and jack into it separately
to work on it.

Actually, you've described precisely what routers do, by definition.
They join two (or more) networks together, but some SoHo NAT routers
don't expose the chunk of functionality that provides the "or more" part
of the equation. They let you join two networks together (your LAN and
the ISP network) and call it a day. Third party firmware will restore
the missing functionality, by which I mean the hardware is always
already capable and if your router can't straddle more than two
networks, it's a software limitation.

However, if your two subnets are cabled through a common switch, you're
already 90% of the way there, with no need to take any part of your
network apart and no need to use a router at all. Simply add a second IP
address to your PC, where the second address lies within the second
subnet. Now you can access both subnets simultaneously. Windows will
figure out which address to use, depending on where you're trying to go.
It should go without saying that you don't need an additional NIC to do
this.

I don't know what the Windows limit is, but as a test a while back I
added 28 addresses to a Win 7 PC, so the limit is somewhere north of
there.

Eric Stevens wrote:
On Tue, 16 Jul 2019 19:56:08 -0400, "...winston"
wrote:

"Eric Stevens" wrote in message
...

I have two computers, 'Corsair' and 'Dell' on an ethernet network
sharing two printers modem. Both computers are running Windows 10 Pro.
Both printers have Internet connections. Corsai has always been a
pain in the plectrum and one of its habits is to keep disappearing
from the network.

It may help to have some commonality across both devices.

Windows 10 (both devices)

Window 10 Pro 1903, both devices.

- Ensure you have a common Windows logon username/password profile on each
device(same name, same password)

I believe I do but my the next question in my series if I ever get
there is why Corsair has from time to time rejected any attempt of
mine to access shared folders and tells me I am not authorised.
Meantime Dell is happy to accept me. But lets not get into that for
the timebeing.

- Do not configure either device to auto logon

Nope.

- Ensure sharing is configured(since you can connect, it most likely it is)
with folders(shared on each device)

Already done.

- Ensure each device is configured for the same work group

There is a problem in that area. Smetimes they are the same. Sometimes
they are not. At the moment they are not.

- Different Computer name on each device(if you've configured both with the
same name, change one)

Corsair and Dell, as per this thread.

= Remember the ComputerName for each device(you'll need it later)
e.g. One Computername Corsair, the other Computername Dell. For
networking purposes when a need to enter the computer name it would be
entered as \\Corsair and \\Dell (remember this, it might come in handy)

Done that previously.

Services(set all below to automatic, IWin10 may reset one of more of the
first two items to Auto(Triggered), if so reset it to Automatic. All these
services started

Comments below elate to Corsair.

- Function Discovery Provider Host
Running, manual

- Function Discovery Resource Publication
Running, Manual(triggered)

- SSDP Discovery
Not running, manual

- UnPnP Device Host
Not running, Manual

Windows Features and Programs
- SMB 1.0/CIFS File Sharing Support
Uncheck(if present) SMB 1.0/CIFS Automatic Removal
Check SMB 1.0/CIFS Client and SMB 1.0/CIFS Server
= The first(auto removal) is design intent, the latter two not
enabled -all due to security risk.
If willing to ignore the risk, since these features may need to be enabled
disable and enable as noted

https://wdc.custhelp.com/app/answers...-on-windows-10
"SMB 1.0/CIFS File Sharing Support has been disabled on Windows 10
Windows 10 Fall Creators Update version 1709 and higher."

Windows Credentials
On each device create a Windows Credential for the each ComputerName using
the common username/password(suggesting at the beginning of this post, 1st
item under 'Window 10(both devices)'
e.g. If the common Windows Logon is Cameo(username) and password then create
a credential for that \\ComputerName Enter the \\Computername in the
Network field then enter the username Cameo and password in the dialog
creation box. Repeat this process on both machines until you have 2 Windows
Credentials created on each device(one for each \\ComputerName and both with
same username/pw)

I have done this in the past but Corsair has just had W10 1903
reinstalled and I haven't got that far as yet.

Win10 can still be persnickety about connecting due to device other device
not on, sleeping, hibernating, wifi power management turning off wifi.

At the moment both Corsair and Dell are permanently awake.

For the most part, the devices will be accessible on each device and appear
in File Explorer/Network...if not shown in File Explorer under Network, just
enter the \\Computername in the File Explorer address field to access and
populate the shared folders in File Explorer's Navigation and Display pane.

It hasn't worked in the past. I will try it shortly.

Workgroup name
- you set the Workgroup name for each device. Once set it remains
constant. Set it the same on each device. Thereafter Windows just reads
what you've set.
Settings/System/About/System Info/Change Settings/Change/enter the
same workgroup name on each device
- the default name is Workgroup(change it to something you like or
leave as is but ensure it is the same on both devices. It doesn't change
once set.

Services - see previous response(set them all to automatic) and
identical on both devices

SMB 1.0/CIFS disabled on 1709 and higher
- ignore it, configure as previously notified. If not present add the
feature via Windows Features.
- as of 1803 SMB1 was no longer auto disabled - add the feature and
restart the computer.
- If you wish to see the devices in File Explorer/Network its necessary
because the Computer Browser service relies on SMB1.
https://www.tenforums.com/tutorials/107605-enable-disable-smb1-file-sharing-protocol-windows.html#option3

\\ComputerName entry in File Explorer Address bar(didn't work in the past)
- configure the devices as previously suggested, then you can 'try it'

....and to restart the device after making major changes like the above.

Windows Credentials
- when you get around to it, do so

Common username and pw(i.e. Windows logon) on each device
- if you believe you do, verify
- the common username/pw on each device can be a Local account or a
Microsoft account(I prefer a Local and one configured as an Admin account)
- If you wish to access other machines on the network it might be a
good idea to ensure the common account is an Admin account.

Network
- ensure you network is configured in Windows as Private Network(both
both Lan[Ethernet] and Wifi) - Settings/Network and Internet/Change
Connection Properties (or in the same location, click Ethernet and/or
Wifi, click on the connection and set to Private)
- Private Network:
Ensure Network Discovery is enabled and auto setup checked
Ensure File and Printer sharing is enabled
- Guest of Public
The only option that should be checked is 'Turn on File/Printer
sharing'
- All Networks
Enable Public Folder sharing/Turn on sharing
Enable 128-bit encryption
Enable password protected sharing

--
...w¡ñ§±¤ñ
msft mvp 2007-2019

On 17/07/2019 07.45, Char Jackson wrote:
On Wed, 17 Jul 2019 00:56:04 -0400, Paul wrote:

If you try pinging from machine to machine,
does ping work for every machine-combo ?
This is a test that the topology of your
network, is what you think it is.

For example,
I have two subnets which use private addresses,
and you cannot expect the router to "join them
together" in a useful way. so I cannot ping
something on the (isolated) segment. I have to
take the network apart and jack into it separately
to work on it.

Actually, you've described precisely what routers do, by definition.
They join two (or more) networks together, but some SoHo NAT routers
don't expose the chunk of functionality that provides the "or more" part
of the equation. They let you join two networks together (your LAN and
the ISP network) and call it a day. Third party firmware will restore
the missing functionality, by which I mean the hardware is always
already capable and if your router can't straddle more than two
networks, it's a software limitation.

Not really :-)

It is always straddling two networks: the LAN and the WAN.

The case of Paul is different: he needs to straddle *three* networks.
One WAN, and two different LANs. For this you need a router with three
ports or more.

Wait, all home routers come with 4 ports, right? No, they come with two.
Those four ports are in a switch that comes integrated with the router.
They are not 4 router ports.

That said, there are tricks.


However, if your two subnets are cabled through a common switch, you're
already 90% of the way there, with no need to take any part of your
network apart and no need to use a router at all. Simply add a second IP
address to your PC, where the second address lies within the second
subnet. Now you can access both subnets simultaneously. Windows will
figure out which address to use, depending on where you're trying to go.
It should go without saying that you don't need an additional NIC to do
this.

Right :-)


I don't know what the Windows limit is, but as a test a while back I
added 28 addresses to a Win 7 PC, so the limit is somewhere north of
there.




--
Cheers, Carlos.

On Tue, 16 Jul 2019 22:59:25 -0400, Paul
wrote:

Eric Stevens wrote:
On Tue, 16 Jul 2019 14:02:00 -0400, nospam
wrote:

because he has more hardwired devices than available ports on the
router, or he wants to run one cable to another room which has multiple
devices, rather than run multiple cables to each device.

That's the explanation. Two computers and two printers upstairs.
Router/modem at the fibre termination downstairs.

So how is our network diagram now, for accuracy.

Are we missing anything in the diagram ?

Nope. With a bit more information it's still:



Corsair Dell Oki Epson
| | Print Print
| | | |
[=======Switch Netgear GS105.===========]
|
[NetComm NF4V Router/Modem]
|
Internet

On Wed, 17 Jul 2019 12:04:51 +0200, "Carlos E.R."
wrote:

On 17/07/2019 07.45, Char Jackson wrote:
On Wed, 17 Jul 2019 00:56:04 -0400, Paul wrote:

If you try pinging from machine to machine,
does ping work for every machine-combo ?
This is a test that the topology of your
network, is what you think it is.

For example,
I have two subnets which use private addresses,
and you cannot expect the router to "join them
together" in a useful way. so I cannot ping
something on the (isolated) segment. I have to
take the network apart and jack into it separately
to work on it.

Actually, you've described precisely what routers do, by definition.
They join two (or more) networks together, but some SoHo NAT routers
don't expose the chunk of functionality that provides the "or more" part
of the equation. They let you join two networks together (your LAN and
the ISP network) and call it a day. Third party firmware will restore
the missing functionality, by which I mean the hardware is always
already capable and if your router can't straddle more than two
networks, it's a software limitation.

Not really :-)

Yes really.

It is always straddling two networks: the LAN and the WAN.

Right, that's sort of what I said above. "They let you join two networks
together (your LAN and the ISP network) and call it a day."

Note that I didn't call it the WAN, but rather the ISP's network.
Technically, there's no such network called "WAN". From the perspective
of a home user, you're connecting to a portion of your ISP's network,
and in turn they connect to other networks, and so on. All together,
that makes up the WAN, but it's all relative to where you happen to be
standing. One person's WAN is another person's LAN, for example.
Conversely, if I allow public access, my LAN would be part of someone
else's WAN.

The case of Paul is different: he needs to straddle *three* networks.
One WAN, and two different LANs. For this you need a router with three
ports or more.

No, absolutely not. A router needs at least *one* port in order to
straddle any number of different networks. The fact that home routers,
as we've come to know them, have two ports (ignoring the 4-port Ethernet
switch which is really a 5-port switch with one port connected
internally), is purely done for the customer's convenience. More than
one port is not a technical requirement. A single-port router would be
referred to as a one-arm router, or a router on a stick. Likewise, other
networking gear such as firewalls, proxies, load balancers, etc., each
require at least *one* port. After all, you have to be able to bring
traffic in and out, so at least one port is required.

Wait, all home routers come with 4 ports, right?

Many do, but not all. I agree with you that those are simply switch
ports and have nothing to do with the routing function.

No, they come with two.
Those four ports are in a switch that comes integrated with the router.
They are not 4 router ports.

Mostly correct, but drilling down just a bit more, we see that the
actual routing function has just a single port. WAN traffic comes and
goes via that port, but LAN traffic also comes and goes via that port
via a bridge. WAN traffic that has been routed to the LAN is allowed to
cross the bridge, where the other side of the bridge is connected to a
switch port. That uses up one of the 5 switch ports, with the other 4
being presented at the rear of the chassis to be used by the customer.
Conversely, LAN traffic that's destined for the WAN is allowed to cross
the bridge, where it hits the router. IntraLAN traffic never gets past
the switch, so it never crosses the bridge and thus the router never
sees it.

That said, there are tricks.

Tricks? :-)

However, if your two subnets are cabled through a common switch, you're
already 90% of the way there, with no need to take any part of your
network apart and no need to use a router at all. Simply add a second IP
address to your PC, where the second address lies within the second
subnet. Now you can access both subnets simultaneously. Windows will
figure out which address to use, depending on where you're trying to go.
It should go without saying that you don't need an additional NIC to do
this.

Right :-)


I don't know what the Windows limit is, but as a test a while back I
added 28 addresses to a Win 7 PC, so the limit is somewhere north of
there.

Carlos E.R. wrote:

all home routers come with 4 ports, right? No, they come with two.
Those four ports are in a switch that comes integrated with the router.
They are not 4 router ports.

usually the switch hardware allows putting those 4 ports on different
VLANs, unfortunately the firmware almost never supports that, unless you
replace it with openWRT etc

In article , Carlos E.R.
wrote:

Wait, all home routers come with 4 ports, right? No, they come with two.

most have four lan & one wan.
some have less and some have more.

Those four ports are in a switch that comes integrated with the router.
They are not 4 router ports.

that depends on the router and how it's configured.

That said, there are tricks.

no tricks needed.

Eric Stevens wrote:
On Tue, 16 Jul 2019 22:59:25 -0400, Paul
wrote:

Eric Stevens wrote:
On Tue, 16 Jul 2019 14:02:00 -0400, nospam
wrote:

because he has more hardwired devices than available ports on the
router, or he wants to run one cable to another room which has multiple
devices, rather than run multiple cables to each device.
That's the explanation. Two computers and two printers upstairs.
Router/modem at the fibre termination downstairs.
So how is our network diagram now, for accuracy.

Are we missing anything in the diagram ?

Nope. With a bit more information it's still:



Corsair Dell Oki Epson
| | Print Print
| | | |
[=======Switch Netgear GS105.===========]
|
[NetComm NF4V Router/Modem]
|
Internet

I wonder who they wrote the user manual for, on the NF4V ?

https://support.netcommwireless.com/...User-Guide.pdf

The manual is written as if IPV4 doesn't even exist.

Paul

On 17/07/2019 18.28, Andy Burns wrote:
Carlos E.R. wrote:

all home routers come with 4 ports, right? No, they come with two.
Those four ports are in a switch that comes integrated with the router.
They are not 4 router ports.

usually the switch hardware allows putting those 4 ports on different
VLANs, unfortunately the firmware almost never supports that, unless you
replace it with openWRT etc

I did that flashing once. It worked terrible. Home routers have scarce
resources, such as little memory. The web page in the router I flashed
crashes when trying to configure some parts of the router, or takes half
an hour to refresh. Yes, that slow. So many features are not accessible
for configuration unless on text mode.

Other routers that came my way, the openwrt pages say that they are very
difficult to flash.

So I do not think I'll flash any router again... Impractical.

--
Cheers, Carlos.

Carlos E.R. wrote:

Andy Burns wrote:

replace it with openWRT etc

I did that flashing once. It worked terrible. Home routers have scarce
resources, such as little memory.

some do, I used an actual WRT54GS for several years it had 32MB ram and
8MB flash, which was a little tight.

Now I have a UK specific router supplied by BT, but it runs openWRT
nicely, dual core 500MHz CPU, internal VDSL2 modem, 128MB ram, 128MB
flash, usb port for a backup LTE modem

Best home router I've ever had.

the openwrt pages say that they are very difficult to flash.
Yes some very fine soldering required to get an RS232 console hooked up
and flash it in the first place and the one-off bootstrap process would
probably put most people off, but for £5 each, I've 'made' a few for
friends too.

In article , Carlos E.R.
wrote:

all home routers come with 4 ports, right? No, they come with two.
Those four ports are in a switch that comes integrated with the router.
They are not 4 router ports.

usually the switch hardware allows putting those 4 ports on different
VLANs, unfortunately the firmware almost never supports that, unless you
replace it with openWRT etc

I did that flashing once. It worked terrible. Home routers have scarce
resources, such as little memory. The web page in the router I flashed
crashes when trying to configure some parts of the router, or takes half
an hour to refresh. Yes, that slow. So many features are not accessible
for configuration unless on text mode.

that doesn't mean all routers will result in the same experience.

the routers i've used openwrt on do not have any refresh delays or
crashes.

Other routers that came my way, the openwrt pages say that they are very
difficult to flash.

some are and some aren't, and openwrt isn't the only option either.

So I do not think I'll flash any router again... Impractical.

your loss.

Andy Burns wrote:

dual core 500MHz CPU, internal VDSL2 modem, 128MB ram, 128MB
flash, usb port for a backup LTE modem

4x gigabit ethernet, dual band wifi ...

On 17/07/2019 20.46, nospam wrote:
In article , Carlos E.R.
wrote:

all home routers come with 4 ports, right? No, they come with two.
Those four ports are in a switch that comes integrated with the router.
They are not 4 router ports.

usually the switch hardware allows putting those 4 ports on different
VLANs, unfortunately the firmware almost never supports that, unless you
replace it with openWRT etc

I did that flashing once. It worked terrible. Home routers have scarce
resources, such as little memory. The web page in the router I flashed
crashes when trying to configure some parts of the router, or takes half
an hour to refresh. Yes, that slow. So many features are not accessible
for configuration unless on text mode.

that doesn't mean all routers will result in the same experience.

the routers i've used openwrt on do not have any refresh delays or
crashes.

Other routers that came my way, the openwrt pages say that they are very
difficult to flash.

some are and some aren't, and openwrt isn't the only option either.

So I do not think I'll flash any router again... Impractical.

your loss.


Their loss.

It will not work unless I specifically buy a router with openWRT in
mind. And "soldering" is not an option I accept (and yes, I'm quite
competent at soldering). Yes, I am aware that the features offered and
the improved security is good to have. Such is life, we can not have
everything.

--
Cheers, Carlos.