Private server: disconnected and/or impossible to log in

Hello everyone,

We are renting a private server (€10 / month) to be able to play with some friends.
We we are logged in, the game is doing pretty well. But after a period of time (never the same), we are disconnected from our server.

Once it began, it is only written "no response" and we cannot play anymore. We have to wait sometimes 5 minutes, or 10, or 8 hours before being able to play again!!

And it is the same if we are 1,2 or 5.
Happens often during the night (Paris time) between 11pm and 3am, sometimes during the day too.

Help guys! Your game is amazing tho, please give me the trick