Did you try to power the router off/on or reboot the computer ? You can check the connection settings. *Options/Preferences -> General -> Network: Connection -> Settings If you do not need to use a proxy to connect to internet then try to select "No Proxy" if "Use the system proxy settings" or one of the others do not work properly. See "Firefox connection settings": *https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can Boot the computer in Windows Safe mode with network support to see if that has effect in case security software is causing problems. *https://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/ *https://www.7tutorials.com/4-ways-boot-safe-mode-windows-10 You can also do a malware scan. *https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware