situation

Your WebModel and "viflow tracker" both use port 80 – but different ports are required.
The simplest solution is therefore to change the port for "viflow tracker".

Solution

1. Open the httpd.conf file in the \apache\conf\ directory with an editor.
2. Find the entry Listen 80 and change the number to 81 for example.
   
3. Save the changes and close the editor.
4. If necessary, release the new port in the firewall.

"viflow tracker" should now be accessible as follows: http(s)://servername:81