It seems that my installation started to fail sometime after an update. I also have a 16.04 installation as well as Win10 which work fine.
It APPEARS to be a DNS problem, in that I can ping addresses but not domain names successfully, and nslookup succeeds ONLY if I specify a nameserver.
The odd thing is that I've added "DNS=18.104.22.168" to my resolved.conf, AND nmcli DOES show a nameserver configured.
This problem occurs both with wireless (and I manually setup addresses to sidestep DHCP without success) as well as ethernet.
So I'm a bit stumped...thank you!