When I activate IGMP on my C5400V2 to support IPTV, the IPTV works but the internet speed drops dramatically. I tried defining vlan's instead but that did the same. Is there a setting I am missing?

My home has too much concrete and metal in the walls and between the floors so I decided to buy a few M5s about a year ago. Installed 7 of them throughout the house (all using ethernet backhaul to con