Previous post: viewtopic.php?f=17&t=137552
I think I found the cause!
In the IGMP snooping tab, there is only a port for the multicast the receiving device in the Members Port.
EXCLUDE THE ROUTER(WAN) PORT!
IGMP Packets are not flooded!
So I can not see any IGMP Join messages on the ROUTER(WAN) PORT side.
Other switches have an "IGMP Snooping Static Router Port" feature that allows forward IGMP packets to the router port by default.
the Mikrotik switch also seems to need this feature.