First, go into your browser’s settings. Then go to Privacy and Security. Change the safe DNS settings using whatever you are using and replace them with new ones. Second, turn off the internet. Third, turn off the computer or mobile phone. After that, turn on the computer or mobile phone again. Then go and turn on the internet again. Finally, try entering Open AI again in your browser. I do it like this and I can solve this kind of problem. Have a nice day.