HI MarshallArts,
Thanks for reaching out, If you are getting the error 401 Unauthorized we find the main reason that would break this connection and return the error 401 Unauthorized Is if the client has enabled SSO (Single sign on) from the front end of the program. When the client enables SSO this means they only need to log into the AccountRight file using their my.myob email and password and the username and password is now linked and not required. From an API point of view, if the client enabled SSO we no longer need to pass the x-myobapi-cftoken header. A good way to test this is to remove the header and complete a request.
If this did not resolve the issue then we would be looking to see if the client had updated their password. Here is a support note with some more information on SSO https://apisupport.myob.com/hc/en-us/articles/360001479716-Single-Sign-on-SSO-and-cftoken
To disable SSO the customer would need to log into the company file and go to Setup >> User Access > Select username > untick the box on the top left to link to My.MYOB.
