Pinpointed a few sources of disconnects.

The following things makes be disconnect so login screen.

Any usage of any flask.

Clicking the flask (like moving it to inventory, this also happend with a sceptre I bought which now seems to have resolved itself).

Certain spells (gets disconnected 100% of the times a boss casts a lightning spell for example).

These situations have been successfully repeated several times and always results in a disconnect.