I had Geoserver running on an Amazon EC2 instance (Ubuntu) with Apache on port 80. I had to change Apache port from 80 to 8081 and Geoserver is not working anymore.
Port 8081 and 8080 are open on my instance and I can access Apache webpage with http://hostname:8081 but cannot access Geoserver webpage on http://hostname:8080/geoserver/web