[duskwuff]

> If a url is not available to public that does not mean that the url does not exist

Compare the behavior of the following URLs:

http://cisco.workplace.com/

http://contoso.workplace.com/

http://google.workplace.com/

Two of these are real companies that have signed up for Workplace. One is not. See if you can tell which is which.

Now, which of these does http://instagram.workplace.com/ seem most like?

(Of course, it is possible that Meta has done something special to make their Workspace instance behave exactly like a nonexistent one. I can't rule that out. But it would be very unusual for them to build in a confusing special case just for themselves.)