Computers not seeing each other over WAN with Tomato router

Could really use some help here -
My home network has a Buffalo router with Tomato 1 25.7z firmware. I have a box running Vista Ultimate and a notebook with Windows 7 RC1 that I rely on heavily for work, school, printing and media streaming. For the past week or so, I just cannot get them to communicate with each other or any others that may be on the network and I believe the issue has to do with the router. To clarify, both of these connect over WAN and have no internet issues, but my xbox and tv comp(Win7) are both on the LAN and have no issues seeing anything. (When the notebook is connected via ethernet, it will connect to the other systems - but not always the Vista box).
Im unable from ping from the wireless comps via 192.168.1.XXX, but 127.0.0.XXX will reply.
Ive double checked network/file sharing settings, and verified that both Windows 7 systems' settings are identical.
I believe I can rule out firewall interference - Windows firewalls are all down, and all systems are running ESET Smart Security which has been disabled.

My assumption is that this has something to do with the WAN filter on the router but Im lost at this point as to how to resolve it... Any input would be great.