David Wright wrote on Thu, 1 Apr 2021 11:50:56 -0500: "I don't recall your answering Alexander's question: what benefit are you getting from those two lines? Do you have a number of machines at home that are being placed in that domain, whose names you resolve with att's help?"
I don't know, except that having nameserver 1.1.1.1 and 1.0.0.1 in /etc/resolv.conf as Felix suggested results in successful name resolution. My setup is an AT&T BGW210 modem connected by ethernet cable to a desktop which serves wifi for printing and ISP access to my wife's Windows laptop. Before I tried solving the name resolution problem, systemd-resolved may have been disabled(?). I might have enabled it, I'm not sure. # cat /etc/nsswitch.conf # /etc/nsswitch.conf # # Example configuration of GNU Name Service Switch functionality. # If you have the `glibc-doc-reference' and `info' packages installed, try: # `info libc "Name Service Switch"' for information about this file. passwd: compat systemd group: compat systemd shadow: compat gshadow: files hosts: files mdns4_minimal [NOTFOUND=return] dns networks: files protocols: db files services: db files ethers: db files rpc: db files netgroup: nis HTH - Dan

