Did you check your firewall settings, etc?
Does it make a difference if you exit out of Steam/Galaxy and start the game directly from the '..\SteamApps\common\Divinity Original Sin Enhanced Edition\Shipping\EoCApp.exe' program file, by right clicking and running as administrator?
If you check the Event Viewer, does that give an error code or 'Faulting Module' file name that might help identify the cause of the crash?
- click Start (or WinKey-R), then type "event viewer" into the search box. in Windows 10, 'event' should bring up 'View event logs'.
- after starting the Event Viewer, expand 'Windows Logs' in the left column and select 'Application'
- in the center column, look for a recent error (maybe sort by Date and Time) for the game
- check the information under the 'General' tab below the list of events, starting with "Faulting application name..."
If that doesn't help, please email supportdos@larian.com with a dxdiag report (WinKey-R, type in dxdiag and hit enter, then when it finishes loading click on the 'Save All Information...' button and save the report somewhere handy), or reply/PM a Dropbox or Google drive link, etc.
Also check the '..\Divinity Original Sin Enhanced Edition\Shipping' folder, and if there are any CrashDump files being created, zip a few together to include.