Thanks again and yep, I should have thought to reboot the server sooner.
I had a thought after all the above. What if there were two devices in the lan with that same .137 IP? It’s inside the DHCP range but I thought having the router reserve the 137 address for my server would mean no other PC could get it.
I’m gonna check out that angle, move the server to an IP outside the DHCP range next.