Cant connect to devices in different subnet but ping works

I had the idea to place cloud connected devices to a separate VLAN with some restrictions (they should not be able to connect to anything else then the Internet and HomeAssistant). The restrictions are not in place yet, I just created the VLAN with a Wifi accesspoint and connected a Xiaomi Air Purifier to that access point.

I’m able to ping the air purifier from the HomeAssistant terminal. So it seems it is able to connect (at least ICMP), and since there are no restrictions yet I would expect that HomeAssistant should be able to talk to the air purifier device.
Re-authenticated the Air purifier with Xiaomi Miio, that went successful. But now HA is not able to initialise/connect the air purifier. So no control or sensor info is received.
This is what I get:

This all worked fine when HA and the air purifier where in the same VLAN.

Is there something I’m missing here?

Just want to verify; you have confirmed the IP address? I know you ping but since you make vlan device IPs will change and maybe ping another device at same IP?

Thank you, was not aware of this. I’ll have a look at that document and see if I can figure it out.

Activate all logs in the router and see what is going on.