mDNS across APs not working

My home setup: AP1 - Router & LAN - AP2. All running OpenWRT 23.05.2

Each device is configured with iot, lan and guest vlans and are all working. DHCP and DNS are on the router, and the APs have been configured as "Dumb APs" as per the Openwrt guide - firewall, DNS and DHCP turned off.

iot vlan is wifi devices only via the APs. lan is a mixture of wifi (APs) and physical on the router

After adding the two dumb APs I'm trying to get mDNS working, I had this working before adding in the dumb APs so I know it works - I followed this guide: https://blog.christophersmart.com/2020/03/30/resolving-mdns-across-vlans-with-avahi-on-openwrt/

If I connect to a physical lan vlan port on the router mDNS resolution it works perfectly for iot vlandevices attached to both APs. But if I'm on the lan vlan on either of the APs mDNS stops working. But on go to the iot wifi and it works, but only for devices on the AP - which makes me think that's just broadcast resolution rather than mDNS.

I've tried to install avachi on the APs the same as I did with the router (with only the reflector option set, as below (which is the same config for the router as well)), but still no joy:

[reflector]
enable-reflector=yes

Can anyone give me some pointers - I think mDNS isn't being forwarded to the router for resolution

The dumb APs only forward frames and don't need any avahi for that.
Check that the router has a rule to allow the mdns packets from iot vlan.

Thanks - the router allowed I've changed the router firewall rule to allow mDNS from device to any zone, this now means that I can ping devices on the same AP, but not those attached to the other one.

Can you give us an example?