When streaming a movie, how long does Plex buffer the movie before playing it?

Lets say that a friend of mine watches a direct play 1080p video via my plex server. For the video to play smoothly, plex need to buffer a bit of the video first before sending it to him, so that his stream doesnt get interrupt incase his bandwidth gets low for a second or so.

How long is that buffer? And is there a way for me to make the buffering a bit longer?

Each client is different and on most hardware devices it’s not adjustable so there is nothing for you to manage.

In Plex land, if the remote client is stopping/starting due to bandwidth issues the thing to do is set a lower bandwidth requirement on the client so it will download/load as fast as needed.