before you say you had 2 router !
You have one router and one Ethernet switch, you have to be precise because a router and a switch is not the same
so you have one of those :
http://www.google.com/search?q=ethernet+switch&hl=en&safe=off&client=safari&rls=en&prmd=imvnsr&source=univ&tbm=shop&tbo=u&sa=X&ei=MFbtT4CdKsKzhAe_g_yEDQ&ved=0CH0QrQQ&biw=1280&bih=744
in the Ethernet configuration you have an Advance / hardware : how it is set on the 2 ethernet port ?