NFSv4 and Kerberos

After another day of googling stuff, I am out of ideas.

I have a Proxmox VE running, appserver. I want to store backups via NFSv4 on backupserver. I joined both machines using the manual Ubuntu to the UCS AD domain.

But how on earth do I create the Kerberos tasks/entries for the nfs authentication? I’m completely lost between kinit, kadmin, and error messages indicating the client was unknown …