Maybe this post will help:
Well, it took me some time because I was busy with other matters. But I am reporting that it works. Below is the final /etc/config/network
config interface 'loopback'
option ifname 'lo'
option proto 'static'
option ipaddr '127.0.0.1'
option netmask '255.0.0.0'
config switch_vlan
option device 'switch0'
option vlan '7'
option vid '203'
option ports '0t 1t'
config switch_vlan
option device 'switch0'
option vlan '8'
…
I guess just add to bridge vlan:
option vid '203.5'
5 being the "C tag" and 203 being the "S tag"
Got me thinking that this might help with "DSA roaming issues":
Hello Everyone,
I want to bring up two issues that many of us have probably faced: broken 802.11r Fast Transition (Roaming) and intermittent 5GHz connection issues. After some intensive debugging, I've noticed that the common denominator for both problems appears to be the DSA implementation.
After a deep dive into the system logs and configurations, I found that these problems occur primarily when VLANs are being utilized.
Would be like with MikroTik RouterOS CAP manager solution where there is only one VLAN between APs and AP CAP manager, and VLANs are defined on WLAN side .