Not receiving more than 4-5 video player streams

I'm enjoying using Roll20, but I seem to have an issue where I can't see more than 4 video player streams in game. The parties I play with tend to be 5-7 so I can't see 1-3 players. I have a great internet connection (500mbs), and all the players are only broadcasting video (not audio too), so I'm wondering if maybe the issue is software related or maybe router port forwarding?

You've likely run into the soft cap of reliable connections. Many users report reduced functionality after 4-5 connections are passed. The system is actually much better than it used to be, but many people just decide to rely on a dedicated service such as Discord, Skype or Zoom.