Router(s) fail to connect to cable modem

I'm facing one bizarre problem.

Cable Modem (Arris SB6183) seems to be connecting to xfinity fine. Xfinity sees it and reports no problem. 

I can connect my computer directly to the Modem using ethernet cable. 

However, none of the 4 routers I tried can connect to the modem over Ethernet. They just blink the red/orange lights meaning "I see ethernet plugged in but cannot get an IP".

To be sure I ran to nearest electronics store and bought new modem and new router. Same deal.

And I did experiment with multiple ethernet cables.

Any idea what can cause that? Thanks!