its probably something wrong with your addguard app or else with your connection , try resetting all data and cache in FF and turn off addguard that you currently using and see if the problem fixed, and you could try something else for your add guard app, like choose something premium or trust worthy if you are lot concerned about ad's .

TY :D

I tried disabling adguard. And all works fine. I have it on pc and there is no issue with firefox. Tried different apps but adguard is the best for my type of internet browsing. Gonna try resetting Firefox app and see what happens

Hello,

I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution.

Thank you for contacting Mozilla Support.

Seburo said

Hello, I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution. Thank you for contacting Mozilla Support.

the problem is not solved. basically i have to install a certificate into firefox for android but there is no option for such thing.