What is NAT? Can I use it?

Network Address Translation is a way of sharing your internet connection to other devices. In the dormitory, any kind of sharing (hotspot, for example) is strictly forbidden and leads to the immediate ban of the source IP address for at least 1,5 hour.
If you would use new devices, you should register them under registered devices and IP addresses.

If your IP address is got banned, and you stopped the sharing or whatever caused the NAT, you should let us know about it in the error reporting area. The unblocking of the addresses is a manual process.