Win 8.1: DHCP no longer getting an IP address

A Windows 8.1 PC which was set up to connect to a wifi network stopped
connecting to the internet a few days ago. On investigation, I found that it
was not getting an IP address: instead IPCONFIG reported a 169.x.x.x
address. This also happened with another wifi network (an Android phone with
mobile-to-wifi tethering enabled) and with the original router connected by
Ethernet. I tried with the router rebooted, and I forgot and re-added the
wifi connection.

I checked that the DHCP service was running. I couldn't find any DHCP events
in any of the Event Logs, with the exception of service started/stopped
events when restarting the PC.

I also disabled IPV6 to force the PC to use IPV4 DHCP, but no change.

I opened an elevated CMD ("run as administrator") and ran "netsh winsock
reset" which appeared to complete without any error message, and I then
rebooted, but this didn't solve the problem either.

"ipconfig /release" appeared to succeed but "ipconfig /renew" hung and never
completed and never gave an error message - this was also from elevated CMD
prompt.

Setting either wifi or Ethernet connection's IPV4 config to static
IP/gateway/DNS worked fine.


The user had already tried restoring the PC to an earlier restore point from
before the problem occurred, but that failed after a long time with a bland
"could not restore to earlier restore point" error (don't you just love it
when that happens - probably 50% of the time I try to restore a PC to fix
some problem, it fails to do so with that sort of message).


I left the PC with a static IP, choosing one which was within the subnet but
outside the router's DHCP scope, and warnings that it may fail if it was
ever connected to another network which didn't have the same subject and
gateway (ie not 192.168.1.x for IP and 192.168.1.254 for gateway and DNS).


Is there anything else I should have tried before going for the pragmatic
static-IP solution?