Andrew

Yes, those are bridged to br-lan.1 now. No change in capabilities.

You made dual configuration and are rolling dice which one would apply in part or as a whole. - old one, utilising VLAN ID 1 and linking untagged ports together...

It is not much different from swconfig, you have to now make br-lan.vlan in place of eth0.vlan in one place and wire physical ports in other place. Indeed pictured re-use...

If you throw 2 VLAN-s at it it is not possible physically.

I think it is order of parsing network file, you add untagged physical port to bridge, then override it with untagged other vlan port. If you swap sections it goes...

Not all adapters offload VLAN-s (ethtool -k), so in some cases that is slower (like add memcpy in and memcpy out) than nothing.

Vlans are supposedly isolated. No idea what you intend to stich on it.

You have to blindly instrument br-lan.1234 before assigning real ports to it. Wifi or serial helps with mistakes.

You can keep wifi in br-lan while you configure br-lan.1234. alternative is to make non-trivial consistent changes in /etc/config and restart with fingers crossed

@jbsky completely different issue, you need to rise wifi mtu via hotplug to transfer frame plus vlan tag. You do not need wds, just bridge ends of wifi ap-sta or...