Zyxel NWA 1123 repeater mode and VLANs
Seemingly the repeater cannot tag packets. It is not possible to use several IDs on the repeater. Disable VLAN on the repeater or (almost) nothing will work. (12/22/2014, hope Zyxel fixes that)
If you want the data from the repeater put into a VLAN you have to set that ID in the SSID offered for repeating by the Root-AP on the RootAP. All packets from the repeater will receive that ID.
To remotely manage the Repeater it will need a LAN-IP Address supported by that one VLAN-ID (no VLAN meens no managment-VLAN).
The repeater does not repeat other SSIDs defined on the Root-AP. All SSIDs have to be defined locally and cannot be defined on the band used for repeating. This band is effectively "lost" for the repeater, wich is not a bug but a smart decision considering throughput.
Caveat: If you do not specify other SSIDs on the (other band of the) repeater it will offer access to the SSID used for repeating WITHOUT SECURITY; seems to be some fallback mechanism.