When the network is disconnected, you can switch the network, or click the flight mode in the computer settings, then close the flight mode and reopen the supply portal to log in, which can generally solve the problem.
It may also be that your computer memory is too full, and opening the APP is quite full. It is suggested to clean up some computer cache garbage, or delete some uncommon software to speed up the operation of the computer, so that you can log in.
Another less common reason is that there is something wrong with the backstage of the website, and you just need to wait for the backstage to fix it.