Can't forward any port but 80

[beez]

I'm having really weird problem. About two days ago I was able to forward ports, but then it suddenly stopped working, and I haven't been able to fix it. I need to forward a non-80 port (let's say 700, though honestly I could use anything. nothing but the preexisting 80 service is working.)

I know I'm not setting up the service wrong, since I was able to before, and it matches how 80 is set up... And I know the port forwarding in general is working, since 80 goes through fine. I've checked the logs, and there's no mention of attempts to connect through 700. DoS attacks on various ports are showing up, successful connections through 80 show up, but not a peep of even a failed connection through 700. All testing sites tell me 700 is closed, 80 is open.

The router is currently on firmware V1.0.0.34. Rolling back to .32 did not fix it, though I have not attempted any further back.

I'm not the primary maintainer of our network, so I don't know if there's some firewall somewhere tripping me up, but I have tried to look and haven't found anything yet...

Am I making a stupid mistake somewhere? What the heck is going on?