Well, the router needs to pass the traffic to the modem....so yes, the router shuld be your gateway.
Also, do you have IP4 enabled, or only ip6? You should have an IP4 address in there somewhere. Check to make certain that IP4 is enabled as a protocol in the network connections as in the following:
I hope this helps.
"If you can't soar with the eagles, then don't fly with the flock!" - Oliver Sykes; Bring Me The Horizon