The server " " is unreachable. Make sure it's running, double check your network....

Getting this again on 2 of my 3 servers. This happened suddenly after 8 days of waiting for my library to fully materialize. I cannot see the settings, “Server settings are unavailable” so I am at a loss as to what to do. Why would this happen on 2 servers seemingly for no reason? Do I have to recreate the server, and start the waiting again? I’ve had to do this before, and with the volume of media I am trying to add to the server, it’s just a lot of waiting. Computers are fine, they have internal and external network, all are accessible using remote desktop, all other functions are fine. Thanks for any help.