A white screen appears after login if the gameserver is not running, has not had time to load resources, or has crashed.
To check, run the command in the server console:
Bash:
ps aux | grep gameserver
If %CPU (circled number) is around 100 - gameserver is still loading resources (you need to wait).
On my VM (4 threads from 10900 and 16G RAM) the loading process of the minimum configuration (convertserver (only for 3.4), nodeserver, dbgate, gameserver, dispatch, gateserver, java) takes 5 minutes.
