i try to learn setting up a network with openWRT. I can't find a complete explanation for routing basics. I got e few book for that topic but not a complete example for trying to understand the network coherences.
Can you please give me a source for some examples to configure a network like my handdrawing?
You do need more than 254 addresses on your network?
Well, then you can do it the way @frollic suggested or choose a 172.x.x.x network where you can have 65.534 addresses.
But i don't know if all available devices (especially IOT) can be set to use such a network.