Trouble viewing a few ip cameras outside on software

[supersticks]

Hi there I have a setup of a few d-link dcs 2120 and a few dcs5220( all connected wirelessly ) , they all can be viewed inside , outside(from web browser , mobile phone) without any problem. But it seems that when i try to view them & record them outside from the network on the surveillance software (dviewcam,vlc), many of my dcs2120 cams can be detected but they all turn out blank(or even leave a green pixel spot at the corner of the view) when it tries to connect. the dcs5220 cams work fine and one of the dcs2120 managed to get connected too.


I made sure all cams have diff http/ rtsp ports So the thing is I'm not sure whether those which can't be viewed or played , are having a low uploading video stream since its wireless? or are there any settings that i missed out? any help out there?

another question is do i need to open ports for rtp audio & video or just http & rtsp