The plex thing is ok if the WIFI connection at home is consistent for uploading. I get around 20mbps consistently for the uploading. Also for mobile, anything above MP3 really needs 4G. I get decent speeds here (switzerland) around 40-50mbs or more for downloading on cell connection.
It’s proving OK for plex, there’s more initial connection issues with plex, the software and handshaking is not as tight as it could be.
I do like my Dropbox solution… it’s been REALLY reliable. Better than Tidal in fact. As good as Qobuz.
ps… I’m really cranking up the Plex side now… I have added around 12000 album folders to the system, it’s holding up ok. I want to finishing the scanning finally and then road test it on my Note 8 properly via cell connection. No app crashes with Plex (yet), which is nice.