Do you even have IPv6 mDNS traffic? You should be able to verify this with /interface/bridge/filter.
From the DNS help page…
mdns-repeater-ifaces (list of interfaces; Default: ) Once an interface in this list receives an mDNS packet, it will forward it to all other interfaces in this list. Only supports IPv4.
Here’s a nice summary of how mDNS works, how to use it and finally using the new mDNS feature in 7.16.
Hi!
I have successfully managed to push Spotify and YouTube casts through VLANs (macvlan, bridge filters).
Both works perfectly having my phone in VLAN1000 and the TV in VLAN2000.
SSDP and mDNS are both forwarded.
Now I wanted to use Samsung Smartview (and also DeX), but it is not finding the TV.
Do you know by any chance which protocol are they using? Maybe not SSDP and not mDNS either?
Oh, and Windows’s cast is also not getting through.
This is such an elegant solution, rather than trying to see the relevant packets coming in and proxying them to another interface you just bridge everything and drop all the packets that aren’t related to service advertisement.
For your windows cast I think this happens at a wireless driver level so you need to look at the beacons, the technical details of the protocol are linked from this page https://learn.microsoft.com/en-us/surface-hub/miracast-over-infrastructure - I can’t even search for a wireless display without being prompted to turn my Wi-Fi card on, and then because I can’t put it into monitor mode I can’t see those frames
Thank you. Although linked MS article is unfortunately not that informative (technically speaking):
I have temporarily removed the generic “block” rule from the virtual bridge’s filters (that contains my 2 desired VLANs cloned MACVLAN interfaces): this way all traffic is allowed to pass through, and it is still not working.
Do you have any idea on what would worth checking?
Windows cast doesn’t do any anything with mDNS at all 
I think the initial communication happens over Wi-Fi, and not on the network you’re connected to, so you’d need a Wi-Fi adapter that can operate in promiscious/monitor mode.
What is the device you’re trying to cast to? You’d want to start off filtering for everything coming from your client, from the IP and the MAC, and try and narrow down what is going on.
Aha that maybe possible!
I’m using a windows11 notebook as source, and an LG webos TV as sink.
Win11 is joined to Wifi (VLANx)
Tv is wired (VLANy)
mDNS is allowed to pass through between these VLANs.
What I found out is that my computer finds my neighbour’s Samsung TV (which is 100% sure that not part of my LAN).
More strange but matches your suspicion: in case I attach TV to wifi (VLANz), win11 immediately finds it and starts streaming to it.