Cranito21

As Dallarian already mentioned it would be good to provide logs and also the minidump of the crash. Make sure to not start the game again after you crashed until you saved the logs. You can find both in your Documents\BattleForge\Diag directory.
Check if your internet connection is stable. Even the smallest hick up in your connection can disconnect you from the game. Try to play with a wired connection if you're currently using WLAN. At least for a small tests with a few rounds. The game is from 2009 and doesn't have a reconnect feature unfortunately. So once you loose connection, you can't recover it.
Some users keep disconnecting from the server no matter what they do or don't do. For some it really helped, that they play with a VPN. The VPN helps to keep the connection more stable.

If you have Discord, you could receive high quality help in reasonable (48h) time I believe, and probably Devs may know solution to your problem.
However, you'd probably have to provide them with more information including logs.

If you don't have Discord, you'll receive help in here, however, it may be a bit slower. ^^
In future please create thread about similar topic in "technical support" cathegory for better visibility / faster help.