Access control panel on internet

[Ascathôn]

I'll post in this topic so that I don't have to start another thread.

I have some different problems with the remote management. When I restart the router, web access works for a few days. In Status -> Port Forwarding it says that the router will forward port 1100 (which I use for web access) to 192.168.1.1. I can access my router at school.
When I tried to access the router a few days later this did not work. But it was still enabled. In the Port forwarding log the entry with port 1100 is gone.

I have Asus firmware 1.9.2.7 installed.