408 Request Timeout

You took too long. I'm hanging up.

What it properly means

The server wants to shut down an idle connection. Some servers send it without any prior request, and some just close the connection without saying anything.

Class
4xx Client error: you fucked up
Defined in
RFC 9110, section 15.5.9

Get one yourself

This endpoint really answers with 408. Point your client at it and see what it does.

curl -i https://httpcodes.dev/api/408