Settled on ~20mbps on a file that’s 31.1 mbps
Didn’t change anything.
I’m using ethernet, replaced the cable 3 times, jumbo frames off, have replaced the router 3-4 times now, can’t connect to my ONT directly as I’m using PoE, no VPN or antivirus or firewall on either end. Just not sure what exactly to do from here LOL. I’ve contacted my ISP multiple times to no avail, they see Speedtest.net results at full 1gbps, they say it’s working fine.
I’m still confused as to what your setup is and how you’re testing everything 
You said a few days ago that you do not have fiber at your place (where the Plex client is), and you talked about PoE (I assume you mean PPPoE), which is typically used by ISPs for DSL connections. Now you mention the ONT as if it were at your house, but I believe you mean the fiber connection at your friend’s place.
So, if I’m correct,
your PMS is hosted at your friend’s house, which has gig fiber. The Plex clients at your friend’s house don’t have any buffering issue.
the Plex clients with the buffering issue are at your house, which has a different ISP and a DSL (?) connection. If so, what’s the max speed of that?
Sorry, if you’ve already clarified some/all of the above.
No worries, yes I do mean PPPoE, I’ve been considering installing PoE cameras haha.
It’s been a bit since I have tested it locally, but last I checked it was buffering like my issue. Going to run some tests later today.
I currently have a coaxial connection with speeds of 1gb down, 40mbps up, different ISP.
Let us know how that goes, because if it buffers when playback is all local, you can at least rule out the ISPs as the cause.
I had (still do) the exact same problem with my ISP. The speedtest shows full bandwidth and no issue. However, when I do an iperf between me and someone else (outside my network), it shows substantial drops. Speedtests in itself are not a reliable measure for Plex. When there are re-transmissions, packets loss and things like that - things that don’t necessarily impact a speedtest - it can have a very negative effect on video streaming.
Not saying it’s your ISP’s fault (in my case, it is). But it could very well be their fault. You wouldn’t be the first whos ISP throttleled video streaming bandwidth.
Also, what VBB said. Check if you get buffering when playing back from the local network (the same network the server is on). If it buffers there, the problem is definitely not your internet connection.
One thing to note is depending on your OS, iperf is not reliable whatsoever. iperfs builds on Windows are incredibly outdated and just aren’t reliable. Assuming you got Linux tho, what ISP are you having issues with if you don’t mind? I am currently used Xfinity on my client side.
@VBB I’m playing a 45mbps movie, the same one I’ve been using to test, locally. Have 200-300mbps on wifi, buffering like crazy still like it was at my home. I would connect via ethernet but the TVs port is only 100mbps. Playing the same file off of my Macbook Pro locally and it’s running just fine. Remote from a friends end plays just fine from my macbook as well, but has issues from my server. Could it be the whole motherboard line??
I can’t speak about Windows. I never touch that trash. I am on Linux. iperf3 is consistently showing less bandwidth than I have, and depending on the other side, causes a considerable amount of retransmits (over 50 per iperf connection). None of that is visible in a web based speed test, where I get full speed.
Luckily, I am on a business internet connection and my ISP has already confirmed to me that there is indeed an issue on my uplink. Just waiting for them to resolve it. Had I not used iperf to troubleshoot this and relied on those web speed tests alone, I would probably still be troubleshooting and never contacted my ISP.
I wonder if there’s a similar program to iperf3 for Windows, I’ve been using OpenSpeedTest but am unsure if it acts the same.
New motherboard fixed my issue. Intel(R) Ethernet Controller (3) I225-V instead of the Realtek 2.5gbe Family Controller. If you’re experiencing an issue similar to mine, check if you’re using the Realtek 2.5gbe Family Controller and get a buyback/model change.
