Multicast and Spanning Tree are the two reasons why I recommend that customers only use high-quality unmanaged switches on their networks. Layer 2 and 3 managed switches are great, but often times their defaults are not conducive to the way that a number of plug-and-play consumer products implement their communication. This isn’t a problem with Roon or Sonos or UPnP, but rather the fact that in a commercial environment the kind of “overly-chatty” traffic that these devices generate is rarely seen and in its default configuration a Cisco SG200 switch will pretty much implode the network trying to deal with it.
Now throw in a router with a questionable multicast implementation along with some wireless access points that simply can’t be configured and you can be royally screwed. For instance Apple’s Airport Devices don’t implement spanning tree correctly and when paired with a manged switch Sonos simply doesn’t work.
I use managed switches at home (mostly because I have them), but had to implement specific parameters on the ports used by Sonos in order to keep spanning tree from booting devices off the network. With UPnP and Roon I’ve had to make some configuration changes to enable Multicast to function correctly (specifically disabling IGMP snooping) and changing the defaults so that the two switches don’t fight over being in charge of all things multicast.
This type of granular control isn’t a big deal if you know the changes that need to be made and can do them quickly, but it does eliminate the ability to be able to plug anything in anywhere.
At the store the audio network is all unmanaged switches and aside from needing to pipe in a VLAN to handle multiple wireless networks on the same access point it’s a completely dumb network. It’s fast but more importantly it’s stable. Last count was over 25 UPnP devices, 8 Sonos, 2 Roon servers and 4 Roon endpoints.
There’s an attitude out there that managed is better (which typically follows along the bigger / more powerful is better attitude that a lot of audiophiles posses), but unless the added features are absolutely required unmanaged will be just as fast and a hell of a lot easier to deal with.
@Alex_Baker make sure that IGMP snooping and “Bridge Multicast” are disabled in your switche(s) and and you’ll also want to be sure that you’re using IP group address forwarding. If you’re using Sonos then there are some changes that need to be made in order to turn off autonegotiation of spanning tree, but this needs to be done on a port by port basis. Also check your router and/or wireless access points to see if they support IGMP snooping and turn it off.