Maybe it's your browser. Maybe it's rush hour when you visit. Check whether the website is correct, see if their website is under maintenance, can't get in during maintenance, and check your network speed.
The solution is:
It is recommended to log in using IE browser instead of other browsers. It is suggested to visit the website at the wrong peak and check whether there are some basic problems such as wrong URL input.
Pay attention to the website announcement, see if you can test the network speed with speed measuring software during maintenance, or find a place with better network speed to log in. If the above methods are not enough, call their customer service phone to ask about the situation.