Secure connection?

@jagauthier said:
That works when Secure connections is both disabled and required.

Did this then not work as expected?
The reasons for this behaviour are still not entirely clear. Is this a viable workaround for you, at least temporarily?

The only remaining advice I have is to go back to my recommendation above and try to configure your router. Which then could make it possible for you to re-enable ‘Secure Connections’ and thus avoid the issue.