Bridge AP to Vlan and mesh does not work

Hi all, 

while having 2 different Wi-Fi networks using Sophos APX (bridge to lan and separate zone) does not work, I decided to delete all wireless configurations and using the following kb to create 2 different Wi-Fi networks. 
https://support.sophos.com/support/s/article/KB-000038265?language=en_US

everything works as expected until I put the 3 APX 320 inside a mesh network. The ap that is connected to the lan port, receives the correct ip in the vlan interface tagged, while the other 2, receive an Ip address from the dhcp enabled on the port. If I disable the dhcp on the physical port, both APs won’t come up. The problem of getting the wrong ip is that both APs won’t give the Ip addresses to clients at all. 
My goal is to create 2 Wi-Fi networks, one for guests and one for internal. Both shall be available through mesh network. 
Thanks