Webstart Workstation connection refused

Products

• CA Application Performance Management Agent (APM / Wily / Introscope)
• INTROSCOPE

Issue/Introduction

Webstart Workstation gets "Connection Refused" when connects to MOM.

Webstart Workstation connects to  Collector EMs without any issue.

Webview connects to MOM without any problem. 

Environment

CA APM 10.7 SP3
RHEL 6.0

Cause

Possible causes: 

1. connectivity
2. Port
3. firewall
4. proxy
5. DNS

Resolution

1. Make sure the computer can ping telnet using the same port
2. Check the firewall 
3. Make sure the Proxy settings 
4. Check any changes on the DNS