In the meantime my pve got another IP address, but .82 is still blocked.
This has to happen in the first-colo.net where shop.maurer-it.com is hosted.
Here is a traceroute from .82
traceroute -T -p 443 shop.maurer-it.com
traceroute to shop.maurer-it.com (79.133.36.249), 30 hops max, 60 byte...