I recently got a new cable model that also acts as a router. I am not super thrilled about it, but this is what my provider gave me. My previous setup was using just a cable modem and my current WiFi router. So, I was able to handle all of my port forwarding via the WiFi router. I still need to use my WiFi router since the signal strength is much better than what my cable modem provider gave me. All of devices are connected to my WiFi router and the WiFi router is connected to the cable model router.
The cable modem router is on network: 192.168.0.1 and my WiFI router's network is 192.168.11.1. The gateway is the 192.168.0.1 address to my cable modem router.
I like the ability to use Remote Desktop to my PCs from outside my network. This was easy before, cause I did not have the cable modem router in between. Now, I am not sure how to tell the cable modem router, which is supplying my WAN IP, to forward all traffic to my WiFi router then have my WiFi router forward the port request to the specific device.
I had tried putting them on the same network, but that didn't seem to work or I did not have the router's configured correctly. Since they were on the same network, I tried adding the port forwarding form the cable modem to my devices. So, I might have setup a port forwarding on 6649 to a local PC 192.168.1.13
The actaul equipment I am using is:
My WiFi Router: Buffalo AirStation Extreme AC 1200 Gigabit Simultaneous Dual Band Wireless Router (WZR-1166DHP)
My cable Modem router: Arris DG860A
Best Answer
If you just want to keep as close to your existing setup as possible, then I would suggest configuring the DMZ in the cable modem (Firewall tab, then DMZ) to point to the IP address that your Buffalo picked up from it. This will forward all incoming traffic to the Buffalo, where you can deal with it from there as you always have.