Urgently looking for someone to fix the server upgrade to Debian 12

urgently. Upgraded from Debian 10 to Debian 12 last weekend. This upgrade (although tested) is not stable. Server goes down unexpectedly, one website hangs on too many redirects (and even adjusting a direct redirect in Plesk doesn't seem to solve the issue. In other words; kind of desparate. I need a SKILLED sysadmin to fix this: VPS: Debian 12 (should be) Plesk, Apache and NGINX. I need a PROVED track record on Debian 12; otherwise don't bother to react. After this upgrade the databases and stuff.