Answer

PROBLEM

• GFI WebMonitor 2013 - Dashboard > Real-time Traffic or Dashboard > Activity > Event Log
• GFI WebMonitor 2015 and later - Dashboards > Real-Time-Traffic or Dashboard > Activity

ENVIRONMENT

• GFI WebMonitor
• All support environments

SOLUTION

1. Make sure your client workstations have their Proxy Settings set (see the GFI WebMonitor Getting Started Guide for options on setting these in your environment). However, for testing, set one of your client's Internet Explorer proxy settings (under Tools > Internet Options > Connections tab > LAN Settings button) to 'Use a proxy server for this LAN' and enter the Internal IP Address of the GFI WebMonitor server and the proxy port (8080 by default - but this can be changed on the Proxy Settings page in the GFI WebMonitor stand-alone edition or in the ISA / TMG Server configuration for that edition). 
2. Attempt to make a connection to an internet site. If it succeeds, check the GFI WebMonitor User Interface in the places listed above (according to version)
3. If the attempted connection fails with a 404 error or other 'Connection Failed' error:

• Make sure all GFI WebMonitor services are turned on (particularly the GFI Proxy Service in the stand-alone proxy version)
• Check the GFI WebMonitor server to see if the Windows Firewall is turned on. If it is, as a test, disable the firewall and re-try your internet connection. If it succeeds and your security policy requires the Windows Firewall be on, then you can add an exclusion to allow access to ports 80 and the GFI WebMonitor proxy port (8080 by default - but this can be changed on the Proxy Settings page).

CAUSE