Time machine recovery issues

[Maus]

Hi all,

 

I'm trying to use time machine to recover some macs across a network, I'm using a Mac Mini with the latest High Sierra update and Time Machine Server. I've tested taking and writing backups to a machine in my office and that works just fine. Problem is, when I go to our classroom and CMD+R to Time Machine, I can see the server listed, but it won't accept the admin credentials.. I've tested two admin accounts and one it shakes, even when it's correct, and the other it just drops back to the server selection screen with no output at all.

 

Any suggestions? I'm pulling my hair out that it works perfectly on one mac, and not on any others.. they're all on the same wired subnet with no firewalls between them, so it's not that.

 

Thanks in advance!