QUIC traffic throttled on AT&T residential

Tue Feb 18 23:43:15 UTC 2020

I've AT&T fiber (in RTP, NC) (AS7018) and I notice UDP QUIC traffic
from google (esp. youtube) becomes very slow after a time.

This especially occurs with ipv4 connections. I'm not the only one to
notice; a web search for e.g. "Extremely Poor Youtube TV Performance"
notes the issue.

I assume traffic is being throttled on AT&T's side. And it's not done
with their CPE; I'm bypassing their NAT box and connecting my laptop
directly to the ONT.

A quick google search shows people are aware that QUIC can look like
DoS traffic -- but how widely known is this problem? It may become
worse if / when sites transition to HTTP/3

For now I reject UDP 443 on the client firewall. Applications using
QUIC client libraries then fallback to TCP. This works well and I have
no issues with latency or throughput when using TCP.

May I naively ask if Google staff are working with AT&T to address this?

-- Dan