Sorry in advance for not reading everything, so if you’ve already went down this path, just ignore. Anyhow, what router are you using? Also, is it up to date on firmware? Any chance any firmware updates coincide w/ Plex updates?
If you can, and you haven’t already, you may try out a different router. I would recommend just using a simple managed switch from your modem to distribute straight to your PMS and your Client device, as a way to rule out any issues w/ the network. I like this one a lot, and it’s only $37…
Linksys 8-Port Business Desktop Gigabit Switch (LGS108)
…we need to definitively rule out anything networking, just to be extra sure, so try different cables if you can as well. You’d be surprised sometimes… it’s just something simple. For you, the defining factor seems to be an older version working well, which points to Plex, but alas, it’s still important to rule out everything else as well, as it can certainly be multiple factors contributing to the overall lack of performance.
Can you hook up a laptop to the end point where your client connects? If so, run a speed test via speedtest.com from there, and also run a speed test straight out of your modem to compare. You could also test your LAN speeds via the lan speed test tool (http://www.totusoft.com/lanspeed) which would be even better.
p.s. apologies for the others in here acting that way, unfortunately, it’s the way of the internet, and people are just… well, like people are. But we can get to the bottom of this issue. Also recommend to post the log files for us, and we can start looking at the software side of things.
