WordPress.org fails to load sometimes when Http3/QUIC protocol is enabled in the browser

[othernoel]

Since at least October 2024, WordPress.org and Tumblr.com fail to load sometimes when the QUIC protocol is enabled in the web browser. Pages would start loading and then get stuck in the middle of the request, timing out after a long time had passed. In some cases, the first few times you access the website would work, but then it would stop working (presumably because Chrome switched to Http3 after the first few requests). I assume this is related to Automaticc's infrastructure somehow as it owns both sites? I've posted about the issue on the forums and on Slack. It has been investigated by Yani and Andrija, but no solution was found.

Yani also reported having the issue when he was accessing from Thailand. I'm from Brazil. It was suggested that this could be an ISP issue. Personally, I never had websites randomly stop loading mid-page like this except for WordPress.org and Tumblr, and if they share the same infrastructure somehow I think that would indicate this isn't an ISP issue. If they don't share hardware or software configuration, then I guess it was just a coincidence.

At the time no issue was posted to the tracker. Ironically, I can't seem to reproduce the issue myself anymore. When I had the issue, I was on traditional broadband, but now I'm on optic fiber. I'm not sure if being on slower Internet is necessary to reproduce the issue. I even assumed it was fixed already, to be honest. I had written a tutorial on how to work around it for Tumblr users by disabling QUIC in the browser, and this week I got a comment saying that the tutorial fixed the issue for them, so I'm going to assume that the issue hasn't been fixed on Tumblr, and it probably hasn't been fixed on WordPress.org either, so it still makes the documentation inaccessible to some people to this day.

Forum post: ​https://wordpress.org/support/topic/wordpress-org-doesnt-load-under-experimental-quic-protocol-http3/

Slack thread: ​https://wordpress.slack.com/archives/C02QB8GMM/p1729425225931729

Workaround tutorial if you need to access the documentation and it doesn't load for you: ​https://www.virtualcuriosities.com/articles/2526/tumblr-doesnt-load-in-web-browsers-because-of-the-experimental-quic-protocol

Considering that this issue is tricky to reproduce and has been investigated already, I'm not sure if there is anything that can be done about it. Maybe if the right person sees this they'll know what to do?

[dd32]

I've escalated this to a network engineer to take a look at.

From the support thread above:

​https://quic.nginx.org/quic.html
You can also disgnose if your browser correctly handles QUIC and there are no obstacles like UDP filtering on the route from your ISP

The first time it showed 100 green (QUIC) blocks, and 900 red (failed) blocks, and the rest became HTTP. I re-ran the test and it was all HTTP.

That suggests that your internet connection is indeed having problems with QUIC, the common denominator between WordPress.org, WordPress.com/Tumblr, and the nginx.org site is that we're all running nginx.
It seems likely to me that the issue is something related to your ISP / network path, and nginx's implementation of QUIC, not specifically something in the configuration on our side.

Notably, WordPress.org & Automattic don't share physical infrastructure, although we have very similar nginx configurations, which is why I'm suggesting it's related to nginx itself.

I would suggest that this is likely something that might need to be resolved in nginx itself, or by your ISP..

I've still mentioned it to a network engineer at Automattic who had recently looked into some nginx+quic things, so if they have any feedback or want extra information I'll pass the details along.

I'm closing this ticket, not because an issue is resolved, but because there's nothing the Meta team can resolve here.