My wesite is not working in static ip address showing ERR_EMPTY_RESPONSE

The past two years my website is working in my WiFi network properly but in the past few days its shows ERR_EMPTY_RESPONSE and its working properly in other IP address and other mobile network. Only the problem in my IP address i just changed my static ip and its working properly for few hours and again the same problem have been appeared. if i ping website and its ip via CMD its shows website is working success fully in my computer.

I already tried the following things

1. Clear all browser history, delete temp and delete prefetch.

2. Fleshed DNS resolver cache.

3. I just changed my static IP to new Static ip but with new static ip its works for few hours and same ERR_EMPTY_RESPONSE repeated again

My website i have been used Front end : HTML, CSS and javaScript and Back end : PHP, Mysql

Please help me and tell me a solution for this problem