Log in page not working. Cannot access dashboard through log in.

I have developed my entire website. set all the settings perfectly. website visitors can register in my website through student registration page. but after registering they cannot log in using the tutor log in page. Please check the video attached. when someone is trying to log in, the browser loads but put the user still in the log in page. the log in is not redirecting people to their respective dashboard. I checked my website users and found that the registration successfully done. but when the registered users trying to log in the event you can see the in video occurring repeatedly. 
N.B.: I checked all my plug in by uninstalling one by one but the problem gets not solved. so the issue is not with the plug ins. What can I do now?

The page I need help with: [log in to see the link]