(In reply to Nathan Wolf from comment #0)
> Current snapshot of Tumbleweed (20210217) breaks DNS namespace resolution. I
> have tried numerous things to resolve this by removing /etc/resolve.conf and
> restarting NetworkManager as well as entering `sudo netconfig update -f` in
> the terminal but nothing seem to restore this. I utilized the snapper
> rollback to snapshot 20210210 to continue to use Tumbleweed. 
> 
> I am not sure what further information I can provide to help with this.

The content of /etc/resolv.conf, the expected nameserver, whether you can ping public IPs like 1.1.1.1/8.8.8.8 and use them for name resolution (dig @1.1.1.1 opensuse.org) would be useful.

Is /etc/resolv.conf a symlink to (/var)/run/netconfig/resolv.conf as it should?

I can confirm this issue after updating to Tumbleweed 20210215 on both the 5.10.16 and 5.10.12 kernels. I tried the same as the OP to no avail.

What I also tried:
- rebooting the router 
- unplugging the LAN cable, restarting the PC and re-plugging the cable
- wicked networking instead of network manager
- another PC running Leap 15.2 and connected to the same cable + router has no issues.

/etc/resolv.conf is a symlink to /var/run/netconfig/resolv.conf

/etc/resolv.conf contains "nameserver 192.168.31.1" (the IP address of my router) as only entry. Deleting that file and restarting nm regenerates this entry. 

I can ping public IPs such as 1.1.1.1 and I can successfully connect to SMB shares on my router. 

dig @1.1.1.1 opensuse.org

; <<>> DiG 9.16.11 <<>> @1.1.1.1 opensuse.org
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached

The solution provided in https://bugzilla.opensuse.org/show_bug.cgi?id=1182107#c2 works.

Then this is most likely a dup.

*** This bug has been marked as a duplicate of bug 118210 ***