Hello, You will need to go into the Sophos settings and find the list of blocked applications. Then remove Firefox from that list. I don't have Sophos installed on my machine so I can't give specific instructions. You may find some more useful information in the article below but again there are not specific instructions for Sophos. [[Configure firewalls so that Firefox can access the Internet]] If you need specific help for Sophos then I would recommend contacting their support department. I hope that helps.