Here is how I got over may problems getting EyeTV working on the iPhone. I suppose the important part of the system is the modem/router, a Netgear DG834PN. Now this device is listed as not compatible with MobileMe and I have never managed to get " Back To My Mac " to work. Today I tried a bit harder.
You have to log into the router, turn on UPnP, then add some "services". You need to add port UDP 4500 for BTMM, TCP 2170 for eyetv. In firewall rules you need to add 3 services, the BTMM service you added, the EyeTV service and the HTTPS service (port 443). for all these services you need to add the IP address of your machine (can be found in system preferences network settings. it might be best to manually fix this in the network settings to stop the router reassigning in on a restart). finally (i think) you need to click on the WAN setup and set your machine as a DMZ server, enter the IP address of your machine. "Apply" all these changes as you make them
reboot the router, either unplug it or reboot from the diagnostics panel. (this part is important)
these processes turned the red "incompatible router" lights off for both BTMM and Use My EyeTV.
This process might not be as clear as it might be, and I am no expert, so I have no idea what all this stuff means, I tried various combinations, the DMZ being the last addition, and all seems to be working.
I dont run a software firewall, but if you do then you will need to punch some holes through that as well. You could test the router settings while the "soft" firewall is turned off.
Stuff often repeated elsewhere, you also need a core2duo processor, EyeTV 3.2, EyeConnect 1.3.6 etc etc and the iPhone app and or a MobileMe account.
hope this helps someone....
cheers
edit: further info:
the whole thing has decided not to work anymore, and I am struggling to make it work again. it stopped without any changes being made. BTMM still shows a green light. My EyeTv now shows red again. Crap!