Disconnecting all the time

For the last 2 months at least I keep disconnecting from the game after each game I complete. I get the same error every time: “Game completed and recorded! Restart Heartstone to continue.”.
It doesn’t matter if I close everything else down on my computer while running the game. I have tested my connection, which seems stable with at least 300/300 but most of the time above 500/500. When I’m thrown out of the game the Desktop App has problems with disconnecting too.

Pls. find a solution. From other threads, it seems like there is a problem with the European server. One has a similar problem on the European server but none on the American. Any suggestions?

(I’ve reinstalled both the desktop app and HS. So far no fix. No other app on my computer or the internet browsers do not have any issues.)