IPTV with H500 LAN Port Stuck when TV channels changes frequently by the user

[pamuditha_abeys]

Hi, 
We are testing IPTV with H500 AP. AP is powered through POE switch. IPTV STB is connected to AP via LAN port. 
Normally TV works without issues. But once we change the channels it get stuck. AP traffic is backhauled locally without using any tunnels. 

Any idea what would happen on this? 

Regards,
Pamuditha

[michael_brado]

Shaun has replied with my suggestion as well, I expect you should see better results, please let us know.

[pamuditha_abeys]

Dear Michael and Shaun, 
Thanks guys for your help. It only required no qos directed multicast on WAN interface. As of now it has resolved the issue. 

But can any one of you explain what would have happened there? Any sort of FIFO queue or something used to do multicast to unicast conversion? 
I have seen some TCP duplicate ACK/spurious re-transmission issues as well during channel changes. 

Regards,
Pamuditha

[pamuditha_abeys]

Thanks for the response. 
It is Cisco SF300 switch. Here the same setup replaced with BelAir AP works fine. So I think switch would not have impact. 
Will try your suggestion and let you know. 

Thanks
Pamuditha