Can't Find Devices/Computers on Network

When I type in "gateway.2wire.net" in my address bar, I get a cannot be found page. Prior to reformating, I could access my router settings that way. Also, I have every computer in my house connected with RealVNC. I used to be able to connect through VNC Viewer by typing in the computer name, now I have to type in the IP (192.68.254.x) - why is this? I had thought it was network discovery, but I already have that on.

Check the Workgroup name on all the pc's, in particular, the reformatted one, and make sure all the Workgroup names are the same.

All of the workgroups are the same.