This page tests browsers and other HTTP clients for compatibility with the 103 Early Hints status code.
Passing means that the client doesn't break when receiving a non-final status code like 103; it doesn't mean that they'll actually do anything with the hints.
Does an image of a green check mark appear?
Make a request to
https://early-hints.fastlylabs.com/test.png; if your client can correctly load that file, it passes.
Did this test identify a problem with your client? If so, please fill out an error report.