An issue during a re-configuration of our proxy service after a certificate renewal caused sites using our shared IPv4 and our preview sub-domains (*.prg1.zerops.app) to stop routing.
Sites with a dedicated IPv4 or using only IPv6 (either directly or behind an e.g. Cloud Flare proxy), were unaffected.
Incident started at 07:58 AM CEST and was resolved at 08:16 AM CEST.