TP-Link TL-MR3420 v2 - AP Mode Tagged VLAN


Trying to setup TL-MR3420 running 17.01.6 as a dumb AP and not being able to. My LAN uplink is delivered tagged and I'm only interested in having it on VLAN 8. I tried multiple things, from the simplest one by just going into the Switch section and changing from 1 to 8 and marking all ports as tagged. Which indeed generates a message about eth1 being renamed to eth1.8. After reboot the device is not reachable anymore from untagged clients but on my upstream switch (Cisco) I see the MAC address as VLAN 1 still.

Is there something I'm missing?