These situations may be caused by such reasons as:
- connection issues;
- interference with the game's performance caused by different apps or configs.
What you can try in this situation:
1) Make sure that you have all required ports opened:
HTTP 80 and HTTPS 443
Also, make sure that these local ports are open (they are required for all game components to work properly):
9977 and 9978
2) Such situations may be caused by your antivirus blocking connection.
Please add your platform (GOG Galaxy or Steam) and GWENT files to the whitelist of your antivirus or just disable it.
3) Make sure that nothing is interfering with the stability of your connection (e.g. downloads/uploads, streams, WiFi issues).
If you are using WiFi connection, please try connecting your PC to the Internet via Ethernet cable while playing Gwent.