STA server status is Down on Gateway vserver though it is reachable from the NetScaler

The hostname should not have extra characters

For Example:

set ns hostName "CTXNETSCALER"

Problem Cause

​In the 14.1 release, a new functionality was added for DDC monitoring. Header "Citrix-UserAgent" is included in http POST request. 

This Citrix-UserAgent header value is in format "Gateway/NS_Version/NS_Hostname/NS_IP". If the hostname contains extra character, the value is wrapped in the next line. Hence it will receive a "400 Bad Request" response

For Example:

set ns hostName "CTXNETSCALER\r"