When trying to launch the desktops through Netscaler users get below error message:

• Verify if it works internally bypassing Netscaler Gateway. 
• If it fails through Netscaler Gateway only, then please take a netscaler trace when trying to reproduce the issue. 
• Open the nstrace and filter it with "http contains ResponseData" to check the response from STA server IP to SNIP as shown below:

• See the IP of server where desktop is hosted, in the XML response as shown above and we could see that desktop is hosted on 10.104.23.15 server IP.
• Filter the trace with that IP and see if there are re-transmissions from SNIP to that server IP as shown below:

• If you are not seeing above packets or you see only SYN packet from SNIP to the server IP where app is hosted then it seems like network issue.
• The reason for this is that port 1494 and 2598 would not be open in the network from SNIP of Netscaler to the VDA server.
• Please have the administrator to check the firewall rules for the same.

Problem Cause

Firewall rules can be the cause of the issue.