When a player is banned on a server because of repeated wrong admin logins, there are 2 ways to fix it..
Method 1: The server owner/admin must manually edit the server.ini to remove the banned IP address:
[Engine.GameInfo] IPPolicies=ACCEPT,* IPPolicies=DENY,123.456.789.123 IPPolicies=
Method 2: Removal by another person who has ingame "adminlogin" admin.
This method might take 1-3 minutes, depending how many IP's are banned on the server from the [Engine.GameInfo] section.
Once logged in as admin, you must use the "admin get" and "admin set" commands.
Enter these console commands until you find the IP of the banned player:
admin get Engine.GameInfo IPPolicies 1 admin get Engine.GameInfo IPPolicies 2 admin get Engine.GameInfo IPPolicies 3 admin get Engine.GameInfo IPPolicies 4 admin get Engine.GameInfo IPPolicies 5etc, It should be somewhere from 1 to 10 (Max of 254), It auto populates from low to high.
Skip 0 as it will never be a player IP, and should not ever be changed.
The answer in the console will be in the format as in Method 1, example: DENY,123.456.789.123
If you have found the IP adress of the banned player remove it with this command:
admin set Engine.GameInfo IPPolicies #Where # = the number you found the banned player IP on.