Optimizing Jitsi

I am new to Jitsi. I have installed it successfully and I am at the moment in the testing phase. However, during testing I realize that in most cases when the users goes up to 6-7 users, i would start seeing black screen on the right thumb tags of the users. When I checked the server for BW allocation, it would barely go up to 2Mbps.

I would appreciate any help that I can get to fix this issue. Right now I am not sure where to look at.

Thanks and Regards,
Safiul Hasan