Wireless Joint

That is correct. There is a few versions that it does work on, as well as the stock firmware, but I burned my 5Ghz radio out with the first release. It may be better now, I would recommend turning the power output down though. The 5Ghz chip was humming! lol.

I haven't tried since the 3/16 release ...

I wouldnt do it as a passthrough, Make the zbt device your "modem". You make the other device handle all the wifi and dhcp and make 2 seperate ip networks.

Connect one port on your zbt to the WAN port of your "dedicated WIFI router"
Thats it for hardware setup

Set the devices to different IP ...

I use Ubiquiti access points for my wifi, much better and reliable. I think TP-Link makes and equivilent type in teh prosumer level. But for ~$100 its so much better than trying to jank a router into ding an access points job. BUT there isnt anything wrong with using what you have! :)

on the ip ...