So when doing a player hosted game, if the host disconnects they leave fine, with no issues.
But clients are sometimes stuck in the server and they eventually get timed out which causes them to disconnect.

Tested it with the Player Hosted Demo and the issue still persists.
It seems though if you run one client through Unity and the other through Steam on a separate account/machine the issue doesn't appear. But doing it Steam to Steam causes issues

After creating a lobby client attempts to start riptide and join the server through steam, joins successfully but then gets rejected with unknown reason logged to console.

Unknown reason = already connected.