Is Multicast / IGMP needed?

I don’t know what IGMP snooping should be good for in common home network setups. It may just lead to problems should devices roam between access points or change from a wired to a wireless connection and reverse as it restricts the traffic to specific switch ports. It may need some time for the changed configuration to propagate or the client (software) has to be restarted to trigger a re-registration for the multicast stream.

According to the manual, there is no way to have more than one port on the ER-X on the same sub-net. So adding a switch seems to be the only way to go if one needs more than just one device per sub-net.


Or use it as a (layer 2) switch only.

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Thanks for the info. That looks like the cause.

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It would seem that Roon just recommend simple, unmanaged switches:

Just like with WiFi over wired Ethernet, there is nothing intrinsically wrong with a managed switch over an unmanaged switch. Roon Labs just recommends against them both in order to avoid the support nightmare that would invariable arise from users who have managed switches but no idea how to configure or use them properly.

There’s a nearly limitless number of ways you can shoot yourself in the foot with a managed switch if you’re not careful.

Roon is wise to make the suggestions they have, but people sometimes read too much into it.

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The difference between the unmanaged smart switch TL-SG108E and the unmanaged GS108 is mainly the built-in IGMP snooping support in the TL-SG108E and so I suspected that this was also the cause of the problems you encountered with it as otherwise there is not much magic involved in “dumb” Ethernet switches but it might also be that the unspecified “Green” functionality of the TL-SG108E was the cause.

As far as support is concerned I have to agree with Roon Labs that for the needs of Roon and typical home network setups a “dumb” unmanaged switch is the best solution (just because users can’t play around with configuration settings). Just be aware that devices like the TL-SG108E and the GS108 are the cheapest of the cheap – the absolute low-end as far as switches go. There can always be quality issues (including issues with standards compliance) and a user might have to buy and try different models in case of problems until he finds a combination that works stable in his setup (but it seems you already figured that out for yourself).

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IGMP Works on my Unifi USG router without any issues. I also have their managed switch no issues at all. It’s essential to section of all the unsecure crap I use for IoT. The only issue with multicast comes when you want to VPN as it’s not passed through or over any vlans. You can configure it but its a real pain to do and my brain is not up to that level of it fun.

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It seems that ER-X actually has a hardware switch chip…

It seems that you can’t assign individual ports to the switch. It’s either a router or a switch but not both at the same time.


Note: I don’t have that hardware at hand and thus can’t confirm if my interpretation of the manual is correct.

But anyway, a simple layer 2 switch should not block IGMP / multicast (Roon discovery). Even my RB750Gr3 that’s based on the same SoC – sometimes we find out things we never wanted to know about in the first place – doesn’t have a problem with it.

Confused but I’ll try and give an educated guess.

A “router” means each port is its own broadcast domain. Roon only works within a single broadcast domain. If want to use 2 or more ports on a “router” within the same broadcast domain you either take that port out to a switch or you build a bridge in the router and assign those ports. Ubiquity documents that here:

Think of it this way…

     |router|IP AddressY|ethernet-MAC1|Port1
     |router|IP AddressX|ethernet-MAC2|Port2


Normal Roon won’t work between Port 1 and 2 (without a bunch of extra work).
Bridged, Roon works fine because you’re on the same broadcast domain.

There is probably some command on that router to enable the bridging to be pushed down into hardware so this won’t impact performance.

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