I have the Deco M4 set up in the folloing configuration.  Main router hooked into the modem and a switch in the basement.  2nd "pod" is upstairs in the middle of the house set up using wifi.  Third "pod" is at the very end of the house set up using wifi as well.  The house is hardwired for internet and I can hook up the second pod using a LAN cable but cant do that for the third pod.  When I hook the LAN cable to the 2nd pod, it kills the entire system and shows everything offline.  I am not sure what I am doing wrong so any help would be greatly appreciated.

Thanks