Reboot the modem and your router, assuming they are two separate devices.
Once both are back up, access the router and delete any DNS settings in there.
See if that makes a difference
Frustrated in my attempt to a) understand why the netbios ‘TexasTea’ (mine) is showing as ‘already in use’ in System Pref/Network/WINS. My Security logs are full of events from this IP. There are lots of other issues I’m attempting to resolve between the laptop and Fios router...