text: **18.1.1 Client issues**
  
  Users often encounter the following common problems when they run client-side applications: 
  
  (cid:2)**Problem**: Client connection received the error Server failed while .... 
  
  **Reasons**: The following areas might cause this problem: 
  
  – Server is not up, or the server is up but not responding to a request 
  
  – TCP/IP problems between Windows and the OnDemand host 
  
  – Protocol problem 
  
  – Firewall problem 
  
  **Resolution**: Check the following conditions: 
  
  – OnDemand library server is up, and it accepts requests. For example, log on to the 
  OnDemand host and issue an**arsdoc**query against the OnDemand system log. 
  
  – You can**ping**the OnDemand host. If not, consult your OS support. 
  
  – The port OnDemand server is listening and ready for a supported protocol. For 
  example, issue the**netstat -tulpn**command. 
  
  – The Linux fire wall is not on. For example, use the**systemctl status firewalld**
  command to turn off the firewall by issuing the**systemctl disable firewalld**
  command. 
  
  (cid:2)**Problem**: Content Navigator or a custom application encounters an error with OnDemand. 
  
  **Resolution**: Test the scenario with the OnDemand Windows client first. If the problem 
  cannot be reproduced, turn on the OnDemand Web Enablement Kit (ODWEK) trace. (See 
  18.2, “Information collection” on page 389). After the ODWEK application programming 
  interface (API) in question is identified from the trace, run a stand-alone program to test 
  the API. (A sample program can be requested from IBM.) 