I wish I could find a screenshot of this but what happens is: You want to modify a GPO that is pushing firewall rules and you go to change them and you get a red box saying something about
cannot connect to the domain only in that section of the GPO, other settings work fine.
The fix is to find your PDC Emulator
Get-ADDomain | Select PDCEmulator
RDP to that DC and then try editing the rules, it will then work!