I have problem streaming IPTV's TV channels on UDP port over wifi to my pc. My current topology is as below

Streaming over UDP with ethernet cable to PC works fine...but I just bought USB wifi adapter so I can stream it over wifi, but somehow over wifi , streaming is not working. VLC just dont play the file and I can see no activity on my wireless network adapter. Is there anything I need to setup in my ADSL router so it can send UDP packets over wifi? I looked at all options in my ADSL modem setup but nothing was there related to this.
As I said, its working fine if I connect through ethernet cable between PC and Modem. It just not working over wifi. does it mean wifi is not capable streaming UDP protocol?
I need help with your expertise guys..I will appreciate your efforts

p.s. IPTV set top box is not necessary to be attached to modem to stream UDP channels on PC. Its just topology for your reference. And ofcource, modem is providing internet access.