Found an interesting option on iPadOS 14+ with self service. If you go to settings and scroll down to Self Service, on the left, you will have a option to turn off Local Network and by doing this it prevents the self service app from communicating with the on prem servers. I haven't found any info on how to force this to stay on. Thought I'd share as I haven't seen anyone mention it and may run into this issue.
Experienced a similar problem with our visitor management app. iPad had updated and displayed the local network devices prompt to the secretary at that building and instead of saying yes she said no. Not knowing that I chased a badge printing problem with it for 1/2 a day until I looked at the app in Settings and noticed that switch.
Doesn't appear as though this is manageable by an MDM. I doubt it will be included anytime soon due to its placement as a security/privacy setting.
I checked two iPad devices running 14.2
One is a student device with restrictions, another one is a teacher device.
Settings (app), Self Service
I only see
Allow Service to Access
Siri & Search
Self Service Settings
(this is blank)
Do you use an on premise server for hosting the JSS? You can also access the local network tab in settings>privacy>Local network.
Here is an article talking about the change on Apples side.