Bad relationship between Modem and Wireless Router.

Here is my problem, it is a bit confusing and hard to explain but stay with me:

Alright, I have a touchstone telephony modem that wont connect to a Netgear wireless N router.

The part that is hard to understand is that the two function fine with other PC's and Consoles but not with each other.

For starters I am getting all of this info from two different setups, however I DO bring my Xbox 360 and Wireless router to both establishments.

I hope this diagram will help to diagnose this problem.

KEY:
HM-home modem
FM-foreign PC
WR-wireless router
HPC-home PC
FPC-foregin PC
XBX-xbox 360
(-)-connection
(~)-wireless connection

HM-WR-HPC~XBX yes
HM-WR-HPC yes
HM-WR~XBX yes

FM-WR no
FM-WR~XBX no
FM-XBX yes
FM-FPC yes (using to make messege)

3-4 weeks ago every thing was all yes.

Because of the mere fact that it changed so suddenly over time I feel as though it is my fault and not the hardware's.(i.e A question more suited for Shelock Holmes than the Geek Squad.)

Please help as soon as possible and please tell me if I am leaving out anything major.

Thank you for reading :)- C.R.