The server has closed your connection; you have been disconnected.

[xpander]

Woaah. Since you tried pretty much everything, there's not much to add really.

-Does it happen with all Characters you have? Maybe if you can try with new/different account?.
Could be some sort of bug with your account for some reason, though it sounds strange.

-Have you checked Windows Event logs to see if WAR.exe leaves some sort of error when it disconnects?
Though i doubt disconnects leave messages there

-Do you have another device/PC/OS installation where you could try the game?
Could even try installing Linux on a spare drive if you have one to test. Time-consuming to test ofc.

I see you already made a bugreport on the tracker also. Probably should continue the info there:
https://bugs.returnofreckoning.com/view.php?id=22922