I'm trying to get a port forwarded, and trust me, I've tried everything. Right now, since the UPnP is enabled and working, the listening port should be unblocked and working, but apparently it's not. Any help would be appreciated. I've already tried the manual way and it still didn't work.

In BitComet, goto Options / Settings and set the Listen-Port to a number of the range 10000 to 65535. E.g. 12345. Now enter your routers setup and configure port forwarding for port 12345 to your computers local ip address.

As I said before, I have already done that and it still didn't work.

Is there another firewall running on the computer? Maybe the windows firewall. If so, you have to open the same port in the local installed firewall on that computer. Have you forwarded the port in the router settings to the local ip of your computer?

I have done both of those. It still doesn't seem to work.