Why is webRTC so glitchy? Code is the same, but "sometimes it doesn't work, sometimes it works"?

I am testing my webrtc application with localhost... It is the weirdest thing. Sometimes it connects perfectly, displaying both local and remote video on both of my windows.

Sometimes on one of the windows it can't display the remote video properly, so the remote video is just "stuck" on one image, and isn't "moving". It's frozen I guess, but the other window can still receive the remote video just fine. So it's like a one sided connection.

Sometimes, the webrtc doesn't even connect at all.

I have gotten all of these things happen, BUT the code is the same... Why is webrtc so weird? Has anyone else had the same problems?