It appears as though your router has 10/100meg ports. There seems to be an issue with the way the CGN3 auto-negotiates speed and duplex settings on anything other than 1 Gig(10/100/1000) ports. I have the same problem with 2 different 10/100 routers bridging to the CGN3. I am purchasing a router with a Gig WAN port to get normal speeds. Currently using the CGN3 in gateway mode and not enjoying it.
The firmware will apply in 2-3 days...seems to apply faster if you are running in gateway mode. It may or may not solve your issue.
