I'm going to try out setting up the management wlan and using that to try out the vlan setup.
you probably also have to change the lan interface to br-lan.10 before you save and apply
A few videos I saw on youtube mentioned that you could do this either way, with a dedicated device or vlan filtering. I don't care either way, as long as it works.
I did read that there's probably a problem with DSA and vlans on my hardware (Xiaomi routers).
I hope it's not that cause I didn't want to run a snapshot version.