I recently got IPTV for my DSL. Included was an multimedia box, which I connected via WiFi: the DSL modem was a Fritzbox 7412, the WiFi was provided by a Netgear R8000, and the WiFI receiver on the multimedia box side was a Netgear EX6200 (yeah, quite heavy setup for simple tasks) . However, IPTV didn’t work properly: few seconds after I picked a channel, the image froze and got stuck.
The solution was to not operate the R8000 in access point mode (routing IP traffic through), but in normal mode providing its own IP addresses. In that mode, it is possible to activate the IGMP proxy in Advanced -> Setup -> WAN Setup. This is the key: the IGMP proxy enables multicasting. Multicasting is needed so that the IPTV traffic is just sent to the devices which request it, and not to all devices (and thus flooding the entire network and freezing the picture).
So if you happen to use a R8000 in combination with IPTV like the “Entertain – Provided by Telekom” from 1&1 – activate the IGMP proxy to enable multicast – and enjoy the show.