Openhabian - separate networks on RPi3

I am now well through building my home automation setup with Openhab. Next week I am expecting my Sonoff switches to arrive and I will be using those with Sonoff Tasmota to control most of the lights in my house (some others will be controlled via z-wave and others via BLE).

One thing that I want to do is isolate the network for those switches from the outside world. Basically I was just thinking of connecting them to a separate wifi router that will be just used for that and nothing else (and completely isolated from the internet). And I was then thinking of connecting my Raspberry Pi 3 via wifi to that router. The Pi would still be connected to my regular local network via ethernet.

The reason why I want a separate router not just a separate network is because you sometimes need to reboot the router because the internet isn’t working or are otherwise messing around with the local network. And I still want to be able to control my lights when that happens.

Does anyone know how to configure Openhabian to do that? Sadly my linux networking is a bit rusty and I don’t really know how to do it. As far as I know it should be possible and pretty easy.

I’m contemplating a similar setup but it would involve more programming on my part - tasmota wouldn’t be compatible, I’d be making my own arduino sketches.

My plan would be to use the pi ethernet for my internet connection then create a special esp8266 mesh WiFi. There are a couple of esp8266 mesh network libraries. They are compatible with mqtt.

So the pi would be on the “real internet” (wired) while the sonoffs and other esp boards would be on their own mesh network… I also don’t know how to set this up. I’m still in the brainstorming stages…

For the WiFi hotspot - this website has a lot of great information. You’d have to figure out the right settings for blocking the outside world and all, but this may be a good place to start:

Hey… A slight update here… In the end I just decided to use my primary router for everything and just use a separate virtual wireless network for the home automation devices.

But I did ask about using wifi and ethernet at the same time over at Raspberry stack exchange and this is what I received:

Maybe it will help someone.