There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connection certificates and send their own.

https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites

https://support.mozilla.org/en-US/kb/secure-connection-failed-firefox-did-not-connect

https://support.mozilla.org/en-US/kb/websites-dont-load-troubleshoot-and-fix-errors

What do the security warning codes mean

tried clearing cookies & history , went to network settings & changed proxy setting form use system proxy settings to no proxy. that did not work. a lot of this problem solving I don't understand the terminology. so i lost to what to do. I have uninstalled the browser and reinstalled the same version browser thinking there may have been a bug do to improper or delayed installation do to slow internet downloads. I have Verizon dsl server. also have hard rebooted after each tries.

also all i use for security is windows built in defender, none of the others you listed.

all I have for Addon's is listed below & I did as you said disabled all & I rebooted. Still have issue with not being allowed access to my banking site when I use my login and password.

( plugins ) OpenH264 Video Codec provided by Cisco Systems, Inc Widevine Content Decryption Module provided by Google Inc.

( Extensions )

DASHLANE Version- I tried even deleting, rebooting, this extension with no success. then reinstalled. 6.2148.3

Yes I tried in private mode but no success. Here are a couple of screen shots. I have had no luck in copying and pasting a screen shot. I tried ( right click ) and paste. I tried ( control & V ) to paste. sorry, Do you have a suggestion of how I could accomplish this? Yesterday I replied to your email to me and sent a couple of screen shots that seamed to go through, so I hope that will help you.

I have no problems on my android phone accessing my account it has fire fox vrs. 100.1.2

Today I uninstalled everything Mozilla related shut down cu by hard booting. Then reinstalling 100.1.2, by unchecking the reinstall box that eliminates old settings and extensions. still no success.

Is it possible to check that box, reinstall and still go to my account later to receive my saved favorites (bookmarks)? I just don't want to loose those. I can deal with the other settings and extentions.

here a 2 screen shots you asked for.

One thing I noticed after uninstalling every thing and deleting every thing even in the trash related to old Firefox installers from other uninstalls I had on my desk top, was when received the new installation seemed to recognize me as a repeat customer why? Is is possible that some thing in the registry is recognizing this and fowling things up? If so I may need to go into reg-edit and delete a line or two to get things clean again for a new install. I have had to do this years ago with my old desktop. If so let me know exactly what to do and what to look for.