Hi Jon,
We were unable to reproduce the reported issue with the sample you have shared. We suspect that the issue occurs due to some network problem. Kindly share the error details and controller code. It will be helpful for us to investigate further and provide details.
And our online serviceUrl is only for demo purpose. We request you to create you own web service by using below documentation link
Kindly try it and revert us, if you have any concerns about this.
Regards,
Dhivya.