Can't use Hubs between VLANs

[VCTGomes]

I usually use IoT VLAN and my mainly VLAN, where HomeAssistant is installed. I have dozens of devices on IoT VLAN communicating with HomePods on mainly LAN, thankful to mDNS replicate and firewall.

However I can't replicate same with Alexa, that can't connect with Matter hub if Echos are on IoT LAN and Matter Hub on Mainly LAN.

Anyone knows what's wrong? Why can't Alexa connect through VLANs?

[t0bst4r]

Unfortunately I cannot help, because i don't have a VLAN setup and never needed to configure/maintain one.

If you find a way to get it working, please feel free to adjust the readme and add a FAQ.

[Apollon77]

Hm ... then it would interesting to find out what's the difference because there should be none. Matter Hub announces itself via MDNS and received UDP ... the same as other Matter devices .. if you find out whats different that would help

[tescophil]

Sounds like you need a mDNS reflector between your VLANS

[Apollon77]

@tescophil As said: MDNS is not enough ... needs to be UDP in general when

[tescophil]

No, it uses both.., from the Matter standard...

"Transport and IP Framing
This layer manages the transmission of the payload through the IP network to the peer device. It uses either the Transmission Control Protocol (TCP) or the combination of User Datagram Protocol (UDP) with Matter’s Message Reliability Protocol (MRP). The MRP implements retransmissions, provides confirmation of delivery, and ensures that duplicated messages are rejected."

[Apollon77]

hehe ... not really (currently) ... Spec and reality is a bit of a difference!
TCP was mainly added (aka "is partially no longerprovisional") in Matter 1.4 and will be used mainly for "large message" usecases like OTA updates and coming camera support or such.

The reality is that TCP is 100% optional for devices and (near to) no device on the market uses TCP at all. This means that Matter in reality as of now uses 100% UDP only.

[JTP335d]

I have a very similar setup with the same results. As a workaround I have home assistant on both networks. I run home assistant as a vm in proxmox and expose both vlans to it which shows up as two nics in home assistant. Home Assistant doesn't really support this though, and it is finicky because home assistant will pick a default and sometimes a reboot will change the default to the IoT and my Apple integration will fail to load. I don't want my Echos on the same vlan as my home assistant. A better option might be to run Matter Hub separate from Home assistant but I haven't explored that.