Network Security causes Thomson TG585v8 router not to respond to web browser

Network Security causes my Thomson TG585v8 router not to respond to web browser on local host. The router continues to function but I am unable to administer it using web interface until the router is power cycled. I wondered if other users have encountered similar issues.

Update to the latest version (12.1.2272): https://forum.avast.com/index.php?topic=187663.0