How to allow subnet communication for my guest network?

Hi there,

I have two subnets on my Tomato router:

• br0: 192.168.0.0/24 (VLAN: 1, VID: 1)
  
• br1: 172.16.0.0/24 (VLAN: 3, VID: 3)

The first one is my main network where all my devices are connected to and the second one is my guest Wi-Fi network.

Now, I have an AdGuard based DNS server running on 192.168.0.253:53, which I push to LAN clients with:

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  How to allow subnet communication for my guest network?