I believe AT&T is actively throttling Plex (U-Verse)

Basically what the title says. Here’s why I believe it’s happening. My server is on a 100Mbps D/U connection (non-AT&T). My server and streaming devices are on different networks. I have been using Plex for several years and have a high degree knowledge of IT. My server is fast enough for the 20 plus users that it serves. Most of my videos are 1080p with a 6-30Mbps bit rate. I’ll give more detail if anyone wants to know the specs. AT&T is my only choice as a provider at home. Every user that has AT&T tells me that they have buffering issues and have to adjust the quality. For me the only playable bit rate is 720p @ 2Mbps. Users with other ISP’s have no issue.

Devices I have tried playing movies on:
PS4 Pro (wired and wireless)
iPhone (wireless)
iPad (wireless)
PC (wired and wireless)
Nvidia Shield (wired and wireless)

Network Setup (Home):
U-Verse Modem (75Mbps down verified with speedtest)
Meraki Firewall
Meraki AP
Netgear Switch

Network Setup (Server):
Non-AT&T (100Mbps U/D)
Meraki FW
Meraki Switch
Host Server with scratch drive on a SSD
File Server 15k drives in a RAID 5

Things I’ve tried:
Every settings configuration possible on every device and server. This has been going on for over a year and lurking these forums and reddit has given tons of suggestions. Nothing has worked yet.
Different server
Replaced router, switch, firewall, AP at both locations
Used a different port
Encoded videos to play in a compatible format that allows direct playing to the device
Setup a server on the same local network as the player and there are no issues. *First clue

The only thing that has worked:
Using a VPN on the device playing a movie. That’s it, nothing else.
Example: Play a movie at 12Mbps, buffers every other second. Play a movie at 8Mbps, buffers every other second. Play a movie at 2Mbps and it works but quality is poor.
Turn on VPN and suddenly any movie can be played at any bit rate.

I’m hoping to hear from anyone else that may be experiencing this and please, if you have any other suggestion I’m all ears.

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You ISP “throttling” the video to a smaller bitrate / resolution is likely the case. When you say connecting via a VPN resolves the issue, confirms this (when behind a VPN your ISP is not able to “adjust” the stream as it is encrypted - you probably knew that being in IT tho).

This has been “legal” in the US for a while now; with no more Net Neutrality, well… ISPs what you to pay extra to stream 720p / 1080p / 4k video streams now…


Its an older article, but does a decent job of explaining it.

Have you tried a packet capture?

It could be something is messed up with a router upstream from you. I have seen where the MTU can be low causing an excessive amounts of fragmentation. Iperf could also be used to verify since you can control the packet size.

Edit: BTW I use ATT Gigafiber and I have not experienced any issues with throttling. I travel for work and been all over and not really seen issues related to ATT throttling. But your backhaul maybe different since you are U-Verse.

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Also one other question how is your server hosted? VM, Jail, Docker etc…?

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