below you can find the answer from web hosting company
“From the google speed page tool I notice that Time To First Byte is 1.6 – 1.7 seconds. Even if the developer’s terminal takes 3 seconds, that’s not why the timeout appears. It should inform you or identify in which communication the timeout is made and increase the appropriate limit either from you or from us upon your suggestion. The request timeout in 3 seconds is too short a time”.
Also, i checked the first byte for /weixin-responder and the result was 2403ms.
https://ibb.co/x7BKHB1
Many Thanks
okay, thank you very much about your help. I will ask my host company.
Do you know if cloudflare needs some special settings?
Thank you for quick reply.
Can you give me any suggestion about server set up?
Regards,