I'm still not seeing anything, but it dawned on me that's probably to be expected since my WAN port (ether2) isn't part of my main bridge (bridge1)...
So, I tried including ether2 in bridge1, but didn't see anything different. I disabled and enabled ether2 but that didn't make anything pop up on wireshark.
In addition to following this guide that you linked I also tried filtering for ipv6. I also tried udp.dstport == 37008. No results there.
Oh well, I'll just keep waiting and watching!