Heads Up :
The post you are writing will appear in a public forum. Please ensure all content is appropriate for public consumption. Review the employee guidelines for the community here.
If you're using the correct I/O credentials, try waiting a few minutes in case the sandbox is still initializing. If it still fails, verify you're using the credentials for that specific sandbox and contact DevNet Sandbox support with the sandbox ID.
This is while I am accessing directly the Catalyst 9000 Username as per example, the sandbox it self is functional, please check the snip that I have added.
