|Without answers to what wanderer asked you I will point out, you shouldn't need a second router unless you have need for a separate subnet. |
If you don't have need for a second, separate subnet your setup should be:
Internet >> combo unit >> Switch >> clients
In which case, you would create a port forward on the combo unit (combo unit = combination router/modem/wireless AP) and point it at the DRV
Even with your present setup, correctly configured, you could still forward through that second router if it's configured as part of the LAN. When configured as part of the LAN, the second router would have an IP in the same subnet as router 1's LAN side and would have DHCP disabled. Clients connected to it would get their TCP/IP settings from router 1 and would be able to communicate with all other clients. This requires the two routers be connected LAN port to LAN port
For more info on adding a second router click on my name above in this response and read my “how-to” guide titled, “Add a second Router to your LAN”
If however you setup your second router as a separate subnet (ie: connected from router 1's LAN port to router 2's WAN port) then you would need to create a port forward on router 1 that would point to router 2's WAN IP and then create a port forward on router 2 pointing at the DRV.
Personally, I would recommend you remove router 2, or connect the DRV to router 1. In either case, you would only need to create a port forward to the DRV on the combo unit as it would be directly attached to it.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.