Local Multicast Steam brings down wireless

[Lak7]

Local Multicast Steam brings down wireless....
Unit streams UDP Multicast 239.255.1.1 and once 1 PC or IPTV STB connects, the wireless goes down.
Using Cheap-O Trendnet Wireless Router.
Looking for solution so I can still stream using Multicast IP, but keep wireless up.
I have been unable to get IPTV STB (Mag-250) to play video using Unicast IP - 192.168.1.x.