Some things that can go wrong (if you didn't do it already):
As I understand your description, your router is hooked up inside the linuxmce subnet (Otherwise disregard my answer).
- Turn off DHCP on your router
- Do not use WAN/Internet port on router, only LAN ports
- Set the ip address of the router to something in MCE subnet address space (i.e 192.168.80.NNN)
- Remove the routers ip address from the MCE DHCP address space to avoid conflict. This is done in the MCE web admin.