Using 2 Quantum Gateway G1100 Routers

[#1]

Good morning.  I am trying to get 2 Gateway routers to play nice on the same network.  On the 1st floor, i have a coax feed going into the main(1st) router.  I am using its ethernet ports as well as the 2.4 and 5GHZ radios.  In my 2nd floor bedroom, I have another coax connection.  This is where I want to use the second router.  I'm interested only in its ethernet ports. 

I followed the directions from another post on here, but I am still having issues.  I disabled both wireless radios on the 2nd router, but that didn't help.  The laptop that I used to configure the 2nd router kept its internet connection.  However, the devices that are wirelessly connected to the main router are losing their connections.  There were 2 devices, specifically, that weren't connecting at all.  Everything returned to normal after I unplugged the 2nd router.  What am I overlooking or doing wrong?

[#2 · Accepted solution]

You can't use two rotuers on the same Internet connection.
Issue is that both are trying to connect to the wan. So they fight each other back and forth.

What you need to do is reconfigure one of them to be a wifi extender or an access point.

Google on how to do that with G1100.

[#3]

Yoe exactl,y your best bet is actually chaing the two together (one will us ethe coax connection, the other will be wired to the first one using Ethernet)