Can I port forward between 2 routers? if Router1 is password protected?



New Member
My ISP, had given me a router where the coaxial cable comes, and where I connect directly (via LAN port) to my pc. (they are 4 ports):
Port 1. Directly to my pc.
Port 2. To my D-link wifi router (to serve smart-tv, laptop and cellphones).

Questions are:
Router 1 (the one from my ISP) is password protected, so I cannot enter nor set up anything in that one. All I know about that router are:
DNS1, DNS2, IP and gateway.
I have full control of my Router 2 (wifi).

are there chances, to port forwarding if I make some changes in router No. 2? but not in router No. 1?

If so, let me know, please.

Thanks a lot.