Posted May 27, 2022
high rated

... which leads to:
https://github.com/FriendsOfGalaxy/galaxy-integration-uplay/issues/33
... where you find the solution:
Open the Python file "%LOCALAPPDATA%\GOG.com\Galaxy\plugins\installed\uplay_afb5a69c-b2ee-4d58-b916-f4cd75d4999a\consts.py" in a text editor.
Change line 15 und 16 to:
CLUB_APPID = "314d4fef-e568-454a-ae06-43e3bece12a6"
CLUB_GENOME_ID = "85c31714-0941-4876-a18d-2c7e9dce8d40"
Save, connect (no need to restart Galaxy), stay connected :)
Ubisoft changed the server ID, the plugin had the old values, therefore no connection. Simply change both id's to the values above.

THANK YOU for taking the time to present us a solution. Appreciate ya man. Cheers!