I know apache is running, because when I put the server ip address or the domain name with no ports, the default apache site comes up. When I put the 8080 or 81 port, it says the site can't be reached. I'm a ubuntu novice and tried to search for this problem, but couldn't find the solution. I know it's probably a simple fix, but I don't know where to start.
You might want to start here: https://forum.howtoforge.com/threads/please-read-before-posting.58408/ Make sure to check out the FAQ and if the problem is not solved post the report in this thread.
ISPConfig auto installer should open all the relevant ports on your server upon install, so if you are on LAN and behind NAT router, ensure you have set fixed IP for the server and do forward the required ports from the router to your server IP. You should follow the above advice in asking for help.
Please run the test script from the link that @pyte posted. But I guess that just a port in a firewall might be closed like @ahrasis suggested and this prevents you from accessing ISPConfig GUI.
