Wired connection going through wrong router

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http://unix.stackexchange.com – My son has a problem not getting a cosistant wifi signal in his bedroom so he uses another router wired to the gateway. The problem I have is that when I connect to the gateway his router issues me my IP address and I cannot access the internet. When his router is turned off I have no problem, the gateway issues the correct IP address and I can access the internet. I have this problem on all three distros that I use, two of which use Gnome Network Manager and one uses wcid. I have no problem at all with wifi connections just wired. The gateway address is and his router address is (HowTos)