If you created a 2562 OP Server and tried to login, but you got stuck in the screen below, there's some things you can do to solve it...
1) If the message "A firewall has been detected" appears, probably is because you didn't redirected in your router the ports needed for the game to work.
My router, for example, is located at the address 192.168.0.1. So i had to access it and redirect the doors 2300-2400 and 47624 (udp and tcp) as you can see it below...
2) The firewall can be blocking your game!
There's many ways to add rules or exceptions to your firewall. But, the easiest way i found is just by starting the game and follow the steps bellow...
If you don't know how to do it, just google for some "how to forwarding ports" video tutorials, and watch it.
Windows will then ask you if you wish to open some firewall ports. Just check the 2 boxes and click "Allow" everytime something popups.
Don't forget to restart the game for the changes to take effect.
3) Windows, games, all are made by humans. So they are not perfect! Sometimes, restarting your game, or the PC itself, will solve many problems.