A common problem is the error message “Server not found – Firefox can’t find the server” in Firefox. Many users report encountering this error when trying to load a website with Firefox, even though the website can be opened in other browsers without any problems. If you encounter the same problem, read this article to find a solution.
What causes the “Server not found” error message in Firefox?
Weak Internet connection: Another reason that can cause the “server not found” error may be a weak or unstable Internet connection.