it's been a long time I'm facing the same issue on multiple hypervisors from different server providers (for over a year on my self hosted servers, at Caldera Park in Milan, too):
I'm currently having two hypervisors hosted by Hetzner,
one running, running version 6.3-6, VMs only...
I just purchased my Proxmox VE Community Subscription, "uploaded" the license key using the Subscription view in the control panel but the check fails due to connection timeout.
The server is a dedicated server hosted by Hetzner.
Do you have any idea if the issue comes from them and/or...