I have two machines behind my NAT router. I've had the same setup for years. 192.168.2.1 is my router; 192.168.2.2 is my wife's machine, which runs my webserver; 192.168.2.3 is my machine, has my poker stuff, postgres DB, etc. I've had port forwarding for various things point to each device with no problem. You all should be able to access
http://ddubois.bounceme.net/ ; I've had that redirection service pointing to my subnet for years, with port forwarding doing it's job, but if you tried it now, your browser wouldn't connect (my PocketPc can't anyway).
About a month or two ago I noticed I couldn't connect to the web server, but didn't have a chance to look at it. Well, now I'm looking. And I cannot connect to neither the apache web server nor the ftp server running on my wife's machine. I can ping it, and I can share windows file systems between the two machines(!!), but "telnet 192.168.2.2 80" and "ftp 192.168.2.2" both time out. Using two different softwares would seem to indicate it's not a web server configuration problem.
If I open network settings, the machine reports it is 192.168.2.2 (assigned, not DHCP). If I try to administer my router from both locations, first my wife's, then mine, the router will complain its already being administered by 192.168.2.2. If I try to "telnet 192.168.2.2 80" and "ftp 192.168.2.2" from that machine directly, it connect/works fine. So the machine thinks its .2, and the router thinks it's .2. This indicates it's probably not a mistaken identity problem.
Wtf?