How to hide other participants' cameras in a group call

Question

I have a button to hide the camera for each participant in the group call. Every time I click this button, I want to turn off the video stream to me or in case there are many participants but I only want to show a few videos, for the rest I just want to hear their audio. I want to interrupt the video media stream to save bandwidth, not simply hide the video from the user.

I tried using the following code on the server, but after disconnecting, I can't reconnect using "connect" function , please let me know how to solve it

public void changeStateCamera(String member, int data) {
        WebRtcEndpoint incoming = incomingMedia.get(member);

        if(data == 1) {
            outgoingMedia.connect(incoming, MediaType.VIDEO);
        } else {
            outgoingMedia.disconnect(incoming, MediaType.VIDEO);
        }
    }