Hello.
That was almost 2 years ago, i can not remember. It was about that admin of the host had made some setting they did not work and revert back to the old settings, and after that was working. It was about that PHP did not detect corecttly if it is or not and HTTPS:// connection and about "remote ip from reverse proxy"
But maybe is not the same issue on your case.
I do not have more detail info about this.