like if I download a video on my phone, can I somehow upload that to my Plex server? or do I have to do it the regular way?
There’s a bunch of different ways you could do it depending on where you got the video from. You could set up smb/samba on your server, connect to it via a VPN, and upload the video through a file app on your phone. You could also set up the “arr” stack of software which lets you basically navigate to a website on your phone and when you click download, your server gets a message to download the file.
It depends on how your Plex server is set up. If you have SSH/SCP access to the machine Plex is hosted on, you could conceivably upload it through SCP, but I don’t think there’s a way through the Plex interface itself.
The short answer is yes, definitely. The longer answer about how depends on a ton of details about your setup.
Let’s start with, where are the rest of the files that are in your Plex library saved? (E.g. on a Windows laptop, on a linux server, etc)
a Windows server, made of a Dell Optiplex something or other and some external hard drives.
Great, so you just need to figure out how to get files onto the Windows server from your phone.
Start by setting it up so you can access the server from your phone while you’re on your home network, then get it to work while you’re out and about.
For step 1, I use CX File Explorer app on my phone, which allows you to add network drives.
For step 2, I use Tailscale. I installed it on my server and on my phone. When I toggle it on on my phone, it makes a tunnel right to the server, so then I can open CX File Explorer and move files over.