Solution 1: Setting Correct Time and Date Moreover, you can use any other DNS server like Google DNS to check if your ISP’s DNS server is causing the problem. Also, if you are using a VPN, then either temporarily disable it or change the server for your VPN connection to check if that is the root cause of the issue. But if you firstly visit and then open /anypage, in that case, Firefox will operate normally. For example, if you are visiting /anypage then it will give this particular error. But before moving on with the solutions, keep in mind that Firefox has a known bug to create this type of issue.