Apple Configurator 2, error adding devices to DEP

Today I needed to enroll 40 iPad mini's into our DEP through Apple Configurator 2.

iOS version High Sierra: 10.13.6

Apple Configurator 2 version: 2.7.1

I was able to enroll 30 of the 40.

iPad IOS version: 13.7

All devices are properly connected to our wi-fi network.

On 10 I receive an error:

An unexpected error has occurred with "iPad.

Provisional enrollment failed.

The cloud configuration server is unavailable or busy.

[MCCloudConfigErrorDomain-0x80ef(33007)]

Any idea on how to resolve this issue?