Your problem is that you seem to run a different software (tinyproxy) on port 8080, so you can not access ispconfig. So the issue you have is not related to ispconfig itself, its a network or server setup issue.
There are 2 solutions:
1) Stop and uninstall tinyproxy on your gateway or server.
2) Configure ispconfig to use a different port by changing the port in the ispconfig.vhost file in /etc/apache2/sites-enabled