Newb question multiple streams

Very knew to this so forgive the ignorance. I’m a little confused on how exactly Plex works. Does the video go directly from your server to the device (phone, roku, etc) or does it go to a Plex server and you view from it? Or is it a choice between the 2? If it is a choice what is the downside with it going to the Plex server?

My end goal is to be able to have 3 or 4 people see content from the server. I only have a 6Mbps upload currently. Is this enough for say phone quality for that many people? Are there any tips that you can suggest? I’m only testing it on my PC right now but eventually want to build a server or nas. Are there any tips (like hardware, settings, etc) that would better facilitate having smooth video with multiple (no more than 4) viewers. Thanks

Whatever you have your Plex Media Server isntalled on sends the video stream to the devices/player you are using for Playback. the stream does not go through us. even the web interface at app.plex.tv/web in a browser is only loading the interface from us. the actual content that you are streaming goes from server to your browser.

suggested reading

https://support.plex.tv/hc/en-us/sections/200286217-NAS-Devices

Just to reinforce the BigWheel post, I use an i7 2600K for my plex server, and I routinely stream 5 to 6 concurrent streams to friends/family/users from my server. I just upgraded internet from 5/6ish Mbps up to 10/12 Mbps because when 5 people stream to outside of my cable modem, it worked fine, but was completely saturating the outbound link, which affected some game play stuff, (PC gamer here, so latency counts), so I wanted more headroom. At any rate, just bear that in mind most of my content is 720/1080p content and I recently switched to using the HEVC .265 encoding for space. When trying to decode more than 3 HEVC titles at the same time, the machine starts to chug along doing anything other than just the plex functions.