Google’s Gary Illyes said on Twitter that Google does not support HTTP pipelining. HTTP pipelining is a technique in which multiple HTTP requests are sent on a single TCP (transmission control protocol) connection without waiting for the corresponding responses.
The technique was superseded by multiplexing via HTTP/2, which is supported by most modern browsers.
Check your website
Among many other things, the website audit tool in SEOprofiler checks the server settings of your website. If there are things that keep search engine robots away, the website audit tool will show you these things: