I am still new to networking and I cannot figure out how to setup access to a different subnet
Here is my setup
Main router - 192.168.0.1 - lan and WAN access
Wifi routers (Xiaomi AX3000) plugged in to Main router - wifi access - 192.168.31.1
I can connect to anything from wifi on my lan - 192.168.0.xxx - for example NAS - 192.168.0.100
But I cannot connect from LAN to Wifi subnet for example from my PC 18.104.22.168 to Wifi router assigned IP address by Main router - 192.168.0.184. I have to turn on Wifi card in my PC and use 192.168.31.1 instead. Same goes for wireless printer.
Everything is connected via unmanaged switch - Router, Wifi routers, PC, NAS
How do I access 31 subnet from my lan?
Currently, it seems that your AX3000 is configured as a regular router with NAT+firewall.
You probably want to use a dumb ap configuration which will enable everything to be on a single subnet.
If you have a specific need to have your wifi on a different subnet, you'll need to make a different set of changes (namely, turn off NAT masquerading on the AX3000, allow wan > lan forwarding on that device, and then add a static route of 192.168.31.0/24 via 192.168.0.184 into the main router.
I found a solution. I am going to get a second network card for my PC and plug it into AX3000. There is nothing in AX3000 UI to turn off NAT.
You don't actually need to turn off NAT. All you need to do is turn off the DHCP server and then connect via the LAN port instead of the WAN port. You will want to change the IP of your AX3000's LAN, too, so that it is part of your main network.