I created a media server using my previously-useless Raspberry Pi 3. I
actually had Raspbian on it but when I tried to update it, I got a
bunch of server errors. It was at least 2 years since I really used
it. While I was figuring that out, I used a suboptimal Android TV
stick with eHomeMediaCenter on it to serve up files. It had one USB-A
port and one micro-USB 2.0 port for peripherals. Trash, but it worked.

I stumbled across OSMC in a web search. Kodi/XBMC and I have a
love/hate relationship. The UI by default is crap and I have the
sounds on it. OSMC is slightly... SLIGHTLY better as a UI. I got it
working, had to rearrange some files, and the most annoying part was
that the DLNA server didn't start on boot. Whatever. I went ahead and
updated the OS and added minidlna for good measure. They both kind of
suck as the folder path is too long to get to in most circumstances,
and obviously only media is available.

I found CX File Explorer on GPlay Stare, so I can mount it as an SFTP
device. That's great for me. The video stuff is working, but the dang
SSIDs for the 2.4GHz and 5GHz are the same (thanks, Comcast) which
results in lots of reconnects and subsequent restarting of videos on
Android. It's still flipping awesome to have all those high-res files
available on ANY device.

Software used:

RPi3
===
OSMC
Kodi
minidlna
(Ethernet + Ethernet over Power connection)
===
Android
===
DroidUPnP
VLC
CX File Explorer
===
PC
(Linux Mint)
===
VLC
sshfs (access to more than just media on PC)