When using the config tool to change the port number of Tomcat or changing the tomcat port number in server.xml, the base URL still points to the old port number.

Steps to replicate :
1. Go to system menu and click on General Configuration
2. Check the base URL and note the port number.
3. Go to config tool using config.bat and change the webserver port number from the current one (eg. 8080) to let say 80
4. Save config and restart JIRA
5. Go to system menu and click on General Configuration
6. The base URL still points to the old port number of 8080.

Because of this, the links in Activity Stream still refer to the old port number.

Workaround is to edit the configuration to modify the port number.