WDS bridge issues

I am trying to set up a wireless bridge on a secondary SSID on 5GHz, running tagged VLANs on the switch side. For bridging IPTV, as my IP over CoAX limits multicast to 10Mbps, which does not cut it for HDTV streams.

I have Internet router -> cable/switch/cable -> Office router (Archer C6 v2) -> living room router (TP-Link TL-WDR4300 v1).
I have tagged VLAN on a port on both sides. I have the tagged VLAN leaving the Internet router on inside. Linux machine on my switch can see it on its VLAN interface. So that is working.
I can set office up as WDS AP, and living room as WDS client. Good connection, 300Mbps.

BUT, I never see the DHCP requests on the Office side of the bridge. I run tcpdump on bridge interface in both ends, so I can see it exists in living room.

Any idea why the DHCP request is NOT routed over the WiFi bridge ?

I assume it is my Office router having issues. Shows data on eth0.3 but not on my br-WaooVLAN or my wlan1 IF.

Only way to get it to work is to enable tagged VLAN on my COAX ethernet on the Internet router. It is like my VLAN -> WiFi -> VLAN does not bridge despite solid connection.