On Fri, 19 Jan 2018 18:27:35 -0000, "NY" wrote:

It would have been interesting to see what DHCP traffic is passing between
laptop and router: is laptop failing to request DHCP address or is it
failing to understand the router's (DHCP server's) response? Didn't have a
computer with LAN trace software to look at this.

I agree, it might have been interesting to see what's going on down at
that layer.

You might install WinDump and Wireshark on a working PC to get a feel
for what a successful DHCP transaction looks like, if you're not already
familiar. That would prepare you to do a similar test on the problem
child to see what's different. From reading your description of events,
I'm guessing it's not sending a DHCP request, or perhaps it's malformed
in some way so that the DHCP server rejects it as invalid. Either way,
after not getting a response, the laptop then does what it's supposed to
do: auto assign an APIPA address (169.254.x.x/16).

Is this issue something that used to work until one day it didn't, or
did it never work?

--

Char Jackson