[2.0.73] "Could not establish network communication with server." when joining; server not visible when hosting

[Lightwavers]

What did you do?
Attempted to host game on Lightwavers account. Game does not show up in server list from Lightwavers2 account. Attempted to host game on Lightwavers2 account. Game does not show up in server list from Lightwavers account. Attempted to join random servers in server list; "Could not establish network communication with server." on join attempt from both accounts.

What happened?
Games do not show up when hosting on either account. "Could not establish network communication with server." when attempting to join other existing servers from both accounts.

What did you expect to happen instead? It might be obvious to you, but do it anyway!
Expected to join game and load in as normal as recently as yesterday.

Does it happen always, once, or sometimes?
Always happens.