Firefox uses whatever connection the computer gives it.

Let's make sure your system is clean; Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

Once the above is done; Perform a System File Check to fix corrupted system files Win 7, 8, 10, Vista: https://support.microsoft.com/en-us/kb/929833 Win XP: https://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/system_file_checker.mspx?mfr=true

SFC found no violations. So still no wifi. But thanks.

Opera and Qtweb have same problem.

• 1) Check the computers and make sure they have the modem listed and are Connected. Check the password being used.
• 2) Check the modem. Make sure the correct password is the same. And the WiFi is turned on.

If you need more help, contact your ISP. Have them test/replace the modem.