How to port-forward in “router behind router” configuration

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Good day to all.

First, I’d like to mention that I *did* try to search for relevant threads before posting this message. Unfortunately, the search engine tells me “The following words are either very common, too long, or too short and were not included in your search: “router behind router” “. Note that I tried the search phrase both with and without surrounding quotes.

Anyway . . .

I regularly set up networks where a subnet is isolated from the host router via the WAN port of that separate network’s dedicated router. This inner “ring”, as I call it, is therefore isolated from any access by users on the host router.

This configuration has worked very well for me over the years. However, now I need to do something different.

Specifically, I need to expose certain ports on machines running on the inner ring. I’m not sure how to set that up. I know that I want to give the inner router a static IP address on the host router so that the port stays forwarded to the inner router should the system be reset or power-cycled. But how do I set up forwarding to multiple ports on multiple machines?

Any guidance gratefully accepted.

dwayne

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I have never tried this but here is the suggestion:
Port forwarding is nothing more than a ‘hole’ open for specific Lan IP.
Easier to remember if the external port and the internal port is the same. So I’ll use that.
For gateway 1 (inner router), port forward the port, say, 1234, for both internal and external ports to the Lan IP of the specific PC, say, 192.168.1.234. For trial and test, set it for both UDP and TDP.
On gateway 0 (outer router), port forward the same port number (internal and external), 1234, to the Lan IP of gateway 1, say, 10.10.10.2.
If it works, then turn off either UDP or TDP (but not both) one at a time. Maybe you only need UDP port only (or TDP port only).

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