An external IP address is not a requirement for DEP. That being said, if you do not have an external IP address your machines will only receive their configurations while on a network that can connect to your JSS.

If you want DEP to work for every machine, regardless of location, then yes, your JSS needs an external IP address for DEP to work properly.

Thanks for the info. Now to find out why we are getting this error...

You can use a proxy for JSS to get to Apple and get the info it needs, I believe. That said, client machines can't use a proxy for APNS to receive DEP info...

https://jamfnation.jamfsoftware.com/article.html?id=379

Well the way that DEP works is that when the machine talks to Apple, Apple says to go talk directly to the JSS. The fact that he's seeing the "Configuration Available" screen means that his machines are communicating with Apple and things are good on that end. It sounds like the issue is occurring because the Mac can't communicate with the JSS.

@mlavine yeah- sounds like the Macs are off network at home or something and getting DEP.

Our second test Mac worked without any issue. The tech I am working with then deleted the record for the first one in the JSS and it too worked. We had no prestage configured when first setting up the initial Mac so it seems that might have gummed up the works.