Erpnext Nginx Issue

Hi Team ,
We are facing some issues of port flush or port release like while accessing the Ip address it says:-

The requested URL could not be retrieved
While trying to retrieve the URL:
The following error was encountered:

//Connection to Failed
The system returned:
(111) Connection refused
The remote host or network may be down. Please try the request again.
Your cache administrator is webmaster.//

Then after that we change our default port(80) to some other number like 81, 9020 or 9060
then every thing is normal but we need the default port.

Kindly suggest us