marcogrcr: I faced the same issue, and I was able to fix it by:
1. Completely close GoG Galaxy.
2. Disable IPv6 (search how to disable IPv6 in your OS online).
3. Open GoG Galaxy.
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I figured this out by examining C:\ProgramData\GOG.com\Galaxy\logs\GalaxyClient.log which had the following error:
> [Error][ (0)] [TID 6132][galaxy_client]: An error occurred, Other, while performing request (requestId: 238) for URL '{redacted}' after 10003 ms. Exception: Timeout (connect timed out: [2001:1900:2318:1f03::2]:443), code=0
> [Error][ (0)] [TID 11820][galaxy_client]: Unable to get response for request url {redacted}. Response code Uninitialized.
You can see that the IP address shown there is IPv6, disabling it on my machine did the trick.