R u suggesting turning off the firewall which I can do.
Please, we, non-native English have difficulties to read 'R' and 'u' (it was better:
Are you suggesting that I turn off the firewall, which I can do if needed)
Yes, can you try disabling the firewall to see what you get?
Try a manual update of the program (not only the virus database).
Also make sure your browser is not set to "Work Offline" (this option is generally in the File menu). If it doesn't help, try switching the proxy settings from "Auto-detect" to "No proxy" (I'm assuming you're not connecting to the Internet via proxy).
Left click the avast icon > Settings
Update (Basic) > Details > Proxy