Help with Pihole and InstantOn access point

Hello kind people

My Pihole is connected via eth0 to my living room router

Pihole IP is assigned statically 192.168…/24.

It’s able to act as the sole DNS provider for all internet connections in my living room / lower levels.

I have an InstantOn AP serving upper floors of my house. It’s on its own VLAN 172.0..

I created 2 vlan interfaces in my pi on eth0.10 and wifi with their own static IPs in the 172.0 range but when I set the DNS provider on my InstantOn to the 172.0.. static IP of my Pihole, no devices connecting to the AP are able to access the internet

What am I doing wrong pls ?

Thanks in advance