I have a 3rd party device on my guest network (it's an IoT hotspot which a local company owns). I had them connect it to my guest network to ensure it doesn't see anything on my home WiFi. It's working, but for it to be optimal, it needs a port forwarding rule.
However, when I go into the advanced networking in the Google Home app, I can only see devices on my regular network when trying to create a port forwarding rule, not the hotspot on my guest network (I do see it when just looking at connected devices).
Is this a limitation of Google Wifi holistically, or just in the Home app?
Unfortunately, my understanding is that you can't port forward traffic from your router to devices on the guest network, only the primary wifi network, they're trying to keep the guest network completely isolated from the primary.
I've tried to connect to the router with a web browser to see if there were other configuration options not exposed in the Home app, but I just get a message to use the app. Is there any way to get to some "admin" level mode?
If the product doesn't allow port forwarding on the guest network (which I see as a missing feature), then I'd put the device on the main network if I were able to set up a routing rule that it could only reach the internet and not anything else.
Sorry for the late reply here, but I was able to verify this for you. Port forwarding is only available on the main network. Port forwarding is not possible on the guest network. I can see how you would have a use for port forwarding on the guest network and it's something I can pass along as a feature request to our internal teams. Let me know if you have any other questions.