1. first of all need to check when the user try to log in with other user name and password the error message same or not.
for example try to log in with the user name 'asd' password 'asd'.
when the error message will be "Wrong login data" in this case we can be sure the internet connection correct and the problem 100% the SSL error.

If SSL error then:

1. run internet explorer
2. here you can find the  "Internet Options" (you can find same on the "control Panel" too) and we choosed the "Advanced" tab.
3. on the "Advanced" tab click on the "Restore advanced settings"

 on the "Connections" tab you can find the "LAN Settings" button. click on it and remove the tick from the "Automatically detect settings"