Just read the first couple paragraphs:
https://developers.cloudflare.com/spectrum/how-to/enable-proxy-protocol/
https://cloud.ibm.com/docs/cis?topic=cis-enable-proxy-protocol
https://developers.cloudflare.com/spectrum/how-to/enable-proxy-protocol/
https://cloud.ibm.com/docs/cis?topic=cis-enable-proxy-protocol