That request isn’t even making it to Cloudflare. A timeout message through Cloudflare would get a 524 or 522 error screen.
Can you try a traceroute to your hostname when that happens?
https://support.cloudflare.com/hc/en-us/articles/203118044-Gathering-information-for-troubleshooting-sites#h_b8cebafd-9243-40e9-9c44-d4b94ccd3a87