I/O error on GET request for "https://dev-77125822.okta.com/oauth2/default/v1/keys"

Hello I have this error when I make this request Protect your API endpoints | Okta Developer -using-postman

each time I always have an error in the description ( I/O error on GET request for “https://dev-77125822.okta.com/oauth2/default/v1/keys”) what should I do to correct it, please?

Do you have problems pulling it up in a browser?