Port forwarding doesn't work but DMZ does...??

[DubbaEwwTeeEff]

I'm trying to set up Subsonic for streaming across the internet on an AT&T UVerse connection and something is confusing me. When I forward the appropriate port (15000 for me) any attempted connection times out - but when I set the computer to run in DMZplus mode, the connection goes through without any problems.

Does anyone have any idea why? I would prefer to just forward ports if at all possible, rather than basically disabling the firewall entirely for that computer. The only thing I can think of is that I'm missing another port that Subsonic needs, but I thought it only needed the one you specify in the settings.

[lemay86]

Yeah that is the only port you need. The only thing I can think of is if this is a router are you sure your forwarding it to the right ip. For example I have 12 devices on my router each with a different lan ip of 192.168.1.X where X is from 0 to 50, so I make sure I use the internal ip associated with the device i want to forward too.

If you check that and it still doesn't work I'm at a loss.

[DubbaEwwTeeEff]

I know I set the forwarding for the right IP, because of the way the menus are structured - the UVerse router has you pick a device on the network, then either specify ports to be forwarded or assign that computer as a DMZ and let everything come in. If I'd been picking the wrong computer, even DMZ wouldn't have worked.

I've set up Subsonic with this same computer on two different UVerse home networks and had the same problem both times. I also did it in the dorms at U of M and had no trouble, but I also wasn't connecting through a home network and firewalled router.

I'm currently in the process of setting up Subsonic on a different computer on the same home network (new HTPC I'm working on) - I'll try just forwarding ports first, I doubt it'll work but it will at least rule out something specific to the first computer.



EDIT: Did a little more research. Subsonic didn't work on the new PC either... but what I didn't expect was that setting the PC up as an FTP server resulted in similar problems. FileZilla's logs showed that it was receiving a connection request, but failed trying to send the Welcome message. Even weirder: when testing the port on http://www.canyouseeme.org/, the page reported success and the logs showed that the Welcome message was successfully sent.

Of course, setting the server as DMZ magically made everything work.

I found other people with this same problem (and same UVerse configuration) on other forums, but none of the posts seemed to have the answer. The only thing I can think of to try at this point is connecting from outside my LAN for testing instead of inside, but I don't really have a computer that I could do this from, and I have no idea why that would make a difference.

EDIT 2: I'm an idiot. If anyone else comes across this problem: the external IP won't work from within your own network but will from the outside. I used a VNC connection to an external Linux box to test this - as long as your ports are properly forwarded and not blocked by your ISP, people on the outside will be able to connect. If you need to connect from within your network, use http://localhost/ or the server's internal IP.

In case anyone was wondering, the same issue was going on with my FTP connection... it's still not totally working, but that's obviously outside the scope of this forum.