How to set up guest network on RT-AX86U-PRO

[BosseSwede]

I am not understanding something, can someone please enlighten me?
Wanting to set up a guest network on my router to give guests Internet access while not entering my internal LAN.
I also want to use this as a test bed for devices like Raspberry Pi units which I would use with VPN to access the main network etc.

So I want to be able to define different subnets for the main LAN and the guest network, but I cannot find that when I look at the config.
This is what I found regarding the guest network:

Notice the line named RT-AX86U Pro where its IP on the main LAN is 192.168.119.1 is shown, but no indication on how to define the IP range for the guest network...

Could someone please advice how I can define a different DHCP IP range for the guest network?

The f/w on this router is as below if that matters:

 

[bennor]

Maybe see if setting up a VLAN where you can configure the IP subnet and DHCP server may work. Then see if you can assign that VLAN to the Guest Network Pro network.

[Wireless Router] What is VLAN and how to setup in ASUS Wireless Router? | Official Support | ASUS USA

[Guest Network Pro] What is Guest Network Pro? | Official Support | ASUS USA

Example from the VLAN link above:

The limited ability of configuring a different IP subnet with WiFi clients using Guest Network Pro (with the initial 3.0.0.6.102_34312 firmware) on a RT-AX86U Pro is what drove me back to using Asus-Merlin firmware along with YazFi.