how to turn off access to the internal web UI management access with public IP

I have a WR21 setup with a public IP and I want to turn off access to the internal web UI management access through the cell network. I use digi remote manager so I’ll still have access to make remote updates.

I want to prevent access to the internal web UI management page through the public IP. If a user is local and plugged into one of the units ports I want to allow access.

I have the firewall turn on for PPP 1

I also have the config Network > interfaces > advanced > PPP 1 remote management access set to disable management. From a different computer using the public IP I can still see the page and log in.

This does work for me as you have tried,

Configuration - Network > Interfaces > Advanced > PPP 1

Remote management access: “Drop Down Menu” Currently is “No restrictions”

Changed to “Disable Management” hit Apply, and then saved and it worked.