In order to participate in a live webcam class on Powhow, you must allow download and upload access on ports 80, 1935, and 8080. These are standard ports that most ISPs and firewall settings will allow by default.
If you find that you are unable to participate in Powhow classes when connected to a specific network, then your ISP or Internet Router/Gateway may be blocking the above ports. If you have a laptop computer, test to see if you are able to participate in a Powhow class while connected to a different wireless connection or Internet connection at your local cafe or work place.
If you find that you are unable to participate in a Powhow class on one computer at home but another computer works, then the firewall settings for the computer that does not work may be blocking the ports above. To correct this, use Google to search for how to configure your port settings on your specific firewall software. If you are using a Windows machine, read this article for help opening ports.