Just to make sure, have your ISP test your service.

A communication 'bottle neck' could describe the problem. What were you doing at the time? surfing, watching a clip, reading something . . . . Is this with all websites/pages, some, a few?

Start Firefox using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

Hi, thanks for the kind reply.

The issue takes place oftenly such as surfing or watching a clip. It remains for a couple of minutes (3-4 min) and the connection gets restored afterwards.

I followed the instructions in the webpage. I have almost done all the orders indicated but unfortunately I cannot fix it.

But I didn't understand "ISP test". Should I do something for that?

I have the same exact issue and have not been able to find a solution here. I have tried a clean uninstall/reinstall, and doing a FF "refresh". It's not my internet, it's Firefox. Chrome runs fine when I open it up while FF is having a down moment.

But I didn't understand "ISP test". Should I do something for that?

Testing the ISP ( Internet Service Provider ) means to have your provider check your service.

Use these links to create a new profile. Use this new profile as is. Is the problem still there?

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Type about:profiles<enter> in the address bar.

I created a new profile and then closed and re-opened the firefox. The new profile is now the default. But the problem is still in place.

Try to reset (power off/on) the router.

resetting the router didn't help as well.

I have this problem with Chrome as well since yesterday!!

Could it be because of an update I had in my anti-malware software?

Start your Computer in safe mode with network support. Then start Firefox. Try Secure websites. Is the problem still there?

Starting Any Computer In Safe Mode (web link) Free Online Encyclopedia

https://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/

https://www.digitalcitizen.life/4-ways-boot-safe-mode-windows-10/ +++++++++++++++++++++++++++++++++++++++++++++++ If the problem goes away with the computer in Safe Mode, the problem is with one of the other programs on the system.

As a test, disable your protection programs.

The problem finally went away. I just disabled the web protection of the anti-malware program and both the firefox and the chrome work well!

Thanks a lot for the guidance.

That was very good work. Well Done. Please flag your last post as Solved Problem as this can help others with similar problems.