I have been trying to find the root cause of buffering issues with Plex on my seedbox for months now, and would really appreciate any advice or ideas you have to help me get to the bottom of this. Sorry if the post is a little long, will do my best to sum up my investigation so far.
Some background - my seedbox is being hosted by Online.net - a Dedibox XC SATA 2016 (8C @ 2.4 Ghz Intel C2750 processor, 16 GB memory, 1 Gbit/s bandwidth guaranteed). In general the connection speed is incredibly good. I download torrents with rTorrent, load them in to Plex media server, and stream them to the plex app on my xbox one.
Sometimes it streams perfectly at 2 Mbps, and sometimes even at lower rates it lags so bad that it's unwatchable. When the buffering issues start up I've tried switching to different video formats (resolution, bitrate, container, codec) but it had little to no impact. I've seen excessive buffering occur when plex does Direct Stream, and not happen when it transcodes, it doesn't seem to make a difference. I've ran monitoring tools such as "htop", and CPU is usually low (max of 70% during a spike), and "nload" to see Outgoing bitrate, which averages between 2-5 Mbps for a single 720p stream (if running multiple streams it increases steadily as expected). Unless I'm missing something, I don't think its lack of horsepower or bandwidth on the seedbox side.
It seems to be connected to the time of day. If I'm watching between 12 AM and 5 AM CST I never run in to issues, even at higher qualities. However during peak hours from 5 PM to 10 PM there's nearly always trouble. I have cable internet at home, and my download speeds are always great. Even if many people are using cable in my area at once, only Plex runs in to buffering issues, other apps like Netflix and Hulu will work just fine... even if multiple devices are running them simultaneously.
So I've done fairly extensive testing and monitoring on server side and at home, looking for any choke point, but I just can't nail down a culprit. As a last resort I'm thinking that maybe because the seedbox is in France, and I'm in US, during peak hours the pipes are getting clogged somewhere in between. That said, whether I'm having buffering issues or not, when I ping the server, the response time stays fairly consistent average around 120ms.
Any other ideas what could be going on? Quite frustrated and happy to try anything at this point.