9100EM Router won't port forward

Hello, guys. This is my first time posting in this forum and I really need some help with my router. I'm trying to forward a set of ports for the router- I know the steps to do it and, as far as I know, I shouldn't be having any trouble. However, there's this problem:

Everytime I try and finalize the port forwarding, the router resets. That's fine- some routers do that. But, after it resets, it can't connect back to the internet. Watching the lights on the router, it appears to be resetting over and over and will continue to do so for an indefinite amount of time until I do a factory-reset. When I do that, it connects to the internet without a problem, but of course the port forwarding is erased. This has happened every time and I've tried about six times, now.

I tried searching for anyone else who has this problem, but I can't seem to find anything relating to this specific issue. If there's something indicative with this particular problem, I would very much like to know.

Thanks for any help in advance!