Ok this is how I would do this. I would enable DHCP on the cable router since it has the most people connected to it and disable it on the DSL router. This just set up a static IP for each computer using the DSL and make sure that the gateway is the IP address of the DSL router. If that doesn't work disable DHCP on both router and set them all statically I know that works seen it in other posts where 3 ISPs involved. Not going to lie the first part is an educated guess but should work. Wish I could test it.