A related topic: Set TTL of SSDP discovery
No reply from HE though... 
As I mentioned in that thread, HE uses TTL=1 in its SSDP discovery messages, and this (nonstandard) behavior prevents using it in multi-VLAN environments (without some network magic of course). The first step would be to support other TTL values, then the drivers should be adapted to support these scenarios as well.
E.g. @djgutheinz's awesome [Release] Samsung WiFi Audio driver works fine on local subnet, but it uses the MAC address for device ID (which is null when routing is involved), so it cannot be used in multi-VLAN networks. (I'll create a pull request for him as soon as I have some free time) These kind of issues may arise in other drivers as well...
