Once the routers are connected, can you login to their web UI's and check they have IPs & the correct DNS settings?
It seems like a DNS issue off the top of my head, esp if the PC uses DHCP and connected directly to the CM works.
Make sure the Routers are using DHCP for DNS as well.
But that is my only suggestion at this point...your right, its weird
Edit: Sorry didn't see that you'd reset to factory settings.... even more