I have been using Plex for a few years, now. First, as an app on my Synology NAS, then as of January with PMS 0.9.12.4 installed on a Windows 8.1 desktop PC (file storage still on the NAS).
The PC has 16GB RAM, and an i7-4790 CPU (Passmark over 10k).
From January into July we were able to stream 1080p files without any hiccup in the playback, nor on the PC (1-2 streams, no more).
We stream to the Plex Windows App, Amazon Fire TV, browser (rarely), and ChromeCast via Android phone.
Our wired network is Gigabit, and the WiFi runs off a Netgear AC1900 Router.
In recent weeks we have run into a lot of stuttering and buffering on the PCs using the Windows app and the browser, and Chromecasting, when streaming 1080p (lots of "your network isn't fast enough" errors). I found that lowering the quality from Original to 3Mbps 720p would prevent this. More recently we're seeing this on the Amazon Fire TV box as well, and even with 3Mbps 720p there are now hiccups and buffering.
I can't figure out why this setup would play nicely for 6+ months, and then grind to a near halt. The network has plenty of bandwidth, the CPU is generally not being taxed, and nothing has changed with the hardware.
Does anyone have suggestions on what could be the cause, or the right places to look for problems?
Thanks!