Client Disconnecting COOP - Multiplayer Online

[PC][0.90.11][Online Multiplayer] Client Disconnecting every 5 min.

Summary
From start the game sync up to 100% and we can start playing, unfortunately after about 5 min into any game session, my friend looses connection to the server, and cant re-join even by using the server code. Doesn’t matter if she refreshes the servers, restart the game or change here online/offline status.
Our settings are same region (Europe) and “private” server. Nothing wrong with either internet connections and the only way to reconnect is for me (the host), to restart the server from the lobby and send her a new code.

Seed
#5453514

Settings
We’re using default settings with the only difference being two added custom islands.

Steps
No known issues to why this is happening.

Extras
-Have you tried reloading your save, game or PC? - YES.
-Have tried reinstalling the game? - NO.
-Is there anything else you tried to alleviate the issue? Restarting the game, computer and stable version. It did not work.

Please see this solution at post #50 here.