IPv6 on mobile networks, was Update to BCP-38?

Fri Oct 4 00:04:30 UTC 2019

> Yep I see this on AT&t's post paid network with my Pixel 3A XL as well, one
> place I really noticed it causing issues is with Facebook and Instagram
> where Facebook requires constant captions to view any Facebook links I
> receive and embedded Instagram content in news articles and things of that
> nature often failed load. It is very annoying.

> > Tmobile US, VZ, and Sprint all have IPv6, but only AT&T has this behavior
> > afaik.

HTTP proxies are used by some mobile carriers to down-scale media sent
thru their radio network to reduce bandwidth. They rationalise that,
e.g, a HD video can be down-scaled for a tiny screen with no real loss
of fidelity but a signficant reduction in bandwidth. Similar
strategies apply to almost all compressible media: mp3, jpegs, etc.

More often used outside the US as I recall but sounds like AT&T might
be doing something similar. You could try a mobile fetch of a known
media file via HTTP and HTTPS then compare them for possible insights
(make sure to use a mobile browser to avoid browser-detects).

Such proxies are sometimes used for carrier ad-insertion as well so
one presumes they detest the widespread switch to HTTPS for at least
two reasons.

Mark.