Hi,

I am currently having IGMP issues in my network with two cascaded TL-SG1016DE switches.

The network looks like this: AVM Fritz!Box Router ->  TL-SG1016DE -> TL-SG1016DE with multiple devices connected to the router and the two switches. Additionally two WiFi access points (also AVM, configured in AP mesh mode) are connected, one on each TP-Link switch.

As we are receiving IPTV via multicast via the Router, I have turned on IGMP snooping in both TP-Link switches. At first this works as expected. But as soon a iOS Device joins the WiFi, I see IGMPv2 Leave Group 224.0.0.251 messages from the iOS device all over the network, flooding everything with one packet every few ms.

When turning off IGMP snooping in one of the two TP-Link switches, the flooding stops. There is still the occasional IGMP message, but no flooding.

It seems the iOS IGMP Leave group message is bouncing between the two switches and sent to all ports.

Any ideas / recommendations?

Patrick