as everything was working fine before, so if i am guessing your *new* wifi router is the culprit, so make it to forward ports.
My personnel suggestion: flash the firmware of Linksys WRT 54 Wifi Router with
Tomato Firmware..
it will make your 2300 router to 15,000/- router
there are many advantages of doing so. You can tweak various settings that were unavailable in original firmware + it gives you so much control.
You can setup dynamic-dnssetup, , block websites with keyword filtering, make vlans, run routing protocols i.e BGP or RIP v2 with another routers, setup static DHCP,Quality of Service, port forwarding, security, boost antenna signal to respectable ratios etc.
i don't have this router, but i experimented with my friends router, with default firmware he was getting weak signals in his room and it disconnected often, but now however the signal strength didn't increase much but the connection is stable.