Standard
HTTP/1.1 is the long-standing web protocol version defining text-based request/response messaging with persistent, largely sequential connections.
A dev.to guide walks Laravel apps from HTTP/1.1 to HTTP/3 on nginx, and the part worth reading twice is its admission that the middle step can hurt, because one connection carrying 40 streams stalls on one lost packet.
Reality
A dev.to post works the header-overhead sum for short polling and lands on 102.4 MB/s of pure framing metadata. The same sum separates polling from a held-open connection, and the three protocols in its title all sit on the same side of it.
Reality
A rolling deploy kept serving deleted JSON fields to a slice of traffic while stickiness was switched off in the balancer config, and the connection doing it was an idle socket held by a module-level requests.Session.
Reality
A new arXiv paper describes two amplification attacks that turn a CDN's HTTP/3 front end into a pump aimed at HTTP/1.1 origins. Two CDN vendors have paid bounties and shipped the authors' mitigations.
Reality
Two disclosed DoS techniques turn HTTP/3-to-HTTP/1.1 conversion at six major CDNs into up to 350x load on the origin, with no configuration change by the customer.
Reality