It shouldn't be your router if the ATA is in front of it like you say. The only pieces in play here should be your modem and ATA since your ATA is providing internet to your router from the LAN port. You can check that by unplugging the LAN connection on the ATA, you should lose internet to your downstream devices (router/computers). I would leave the router out of the mix until you get the ATA working. Make sure the cable coming out of the modem is plugged into the WAN port of the ATA (sounds like it is). Turn off the modem and ATA. Turn the modem back on, wait 1 minute (or so) and plug your ATA back in. I am assuming your old linksys router was hooked up the way your new one is (i.e ATA in front of it ).