They could be blocked upstream, or your forwarding is for only the single port the game uses for communication, and not for the ACK port if it is different. Could be your personal firewall is blocking it, could be teh firmware on the router is setup for it but comcast does block port forwarding to specific ports.
Try a online port scanner and see what that shows for the game ports, and your FTP. If it doesn't show open, then you have nothing, but then try opening a common port like 80 or 21 and see if that shows up as open.
Also try turning your firwall completely OFF for the short time the tests anre running if at first it doesn't work.
Make sure your modem has NAT transversal turned on. Opening a port is not forwarding one, unless it asks what port to open on the WAN, and the final IP destination of that port, performs NAT transversal, your firewall is allowing communications with a specified port, and the program is running, and you can force your external IP in the config file somewhere.
I use Qwest and they were supposed to not allow FTP, game, web, and other servers a few years agi, but we hacked into our modems, and did the deed. Now we have these pansy modems they send out that do a piss poor job of networking but at least they have GUI.
Scanning ports on 67.184.184.28
67.184.184.28 isn't responding on port 21 (ftp).67.184.184.28 isn't responding on port 23 (telnet).67.184.184.28 isn't responding on port 139 (netbios-ssn).67.184.184.28 isn't responding on port 445 (microsoft-ds).67.184.184.28 isn't responding on port 3389 (ms-wbt-server).
I am running a trace into a text file now, and we will see where it ends.
1 1 ms <1 ms <1 ms 192.168.0.1
2 27 ms 27 ms 26 ms hlrn-dsl-gw46-238.hlrn.qwest.net
3 40 ms 34 ms 27 ms hlrn-agw1.inet.qwest.net [71.217.189.105]
4 50 ms 50 ms 50 ms dap-brdr-03.inet.qwest.net [67.14.2.89]
5 91 ms 50 ms 50 ms xe-8-1-0.edge2.dallas3.level3.net [4.68.63.49]
6 51 ms 50 ms 50 ms ae-3-80.edge3.Dallas1.Level3.net [4.69.145.136]
7 51 ms 51 ms 51 ms COMCAST-IP.edge3.Dallas1.Level3.net [4.71.198.38]
8 82 ms 82 ms 82 ms pos-0-9-0-0-cr01.nashville.tn.ibone.comcast.net [68.86.85.22]
9 68 ms 68 ms 67 ms pos-0-10-0-0-ar01.indianapolis.in.indiana.comcast.net [68.86.90.174]
10 70 ms 67 ms 68 ms pos-0-14-0-0-ar01.area4.il.chicago.comcast.net [68.87.231.17]
11 71 ms 70 ms 70 ms po-60-ur04.nchicago.il.chicago.comcast.net [68.87.230.42]
12 * * * Request timed out.
13 78 ms 79 ms 78 ms c-67-184-184-28.hsd1.il.comcast.net [67.184.184.28]