Before entering the IP address double check if IP address is correct. Once IP address is
enforced and if you have entered wrong IP address range, administrator can't connect
SharePoint admin center to reconfigure. If you face similar problem, you need to contact
Microsoft support to reestablish connectivity.
If you have already applied Azure Active Directory Premium (AADP) to restrict location access by IP
network range setting, that will take higher precedence of SharePoint admin control access based
on network location setting.
How to find the control access based on network location setting is working?
It’s very simple if you access undefined IP address range, you will get Access
restricted error message and below we have listed all kind of warring messages
like Browser, OneDrive client sync, SharePoint PowerShell (SPO Services, PnP Online).
Browser Warning Message