How to block rough router in a private network

I have been forcefully selected to be the internet admin of my dormitory, but now I realized why previous admins hated to do this voluntary services. We had SonicWall firewall and now Waver and soon Draytek. All of them has one problem; none of them works properly, if there is a router in the network. Because of this the internet is very unstable, and I become the most hated person in whole dormitory. It is impossible for me to play the KGB and go to each room, total 120 and check if any of the student using router or not (Im not getting paid for this). I have thought about router snooping switch. I am not sure, but I assume that DHCP snooping blocks the rogue DHCP connected to the network, but the routers in the network are connected through WAN port and not sharing any DHCP network through WAN to outside. Is there any option to block those routers so my DHCP firewall router can work without any disruption? I would be very grateful, if anyone could provide me a solution.