Fixer said:
I'd put next month's wages on the faulty removal of Homegroup as the cause here, but that apart I've not had problems with my network over the last few years, largely helped by always using fixed IPs IMO.
Yes I agree, I have reverted to this quick fix, to edit the HOSTS file and add in any Desktop that I cannot access, by IP. Not perfect, but they stay OK for long periods on most stable networks. I suspect the real issue is related to IPV6 handling (buggy and not robust yet), and remnants of HOMEGROUP getting in the way as well. The ping for the desktop was ONLY showing up its IPV6 address. For me, this was also needed below to ensure my devices were properly published and seen in the NETWORK view (it was initially only 2 services, but seems to be more recommended to change to Automatic (delayed start).