A timeout occurred Error code 524 on Webmail page

Hi, I want to ask for help. When I login to webmail, there’s no issue, but after I want to open inbox in Webmail, A timeout occurred Error code 524 page come out. Can someone help me how to solve it? Thank you

A 524 error indicates that Cloudflare made a successful TCP connection to the origin web server, but the origin did not reply with an HTTP response before the connection timed out. Review the suggestions in this Community Tip for troubleshooting ideas.