Hello Darryn Hart,
If you are enrollment through Entra ID, You can increase the device quota limit from the Azure portal by navigating to Device settings in Microsoft Entra ID, and updating the Maximum number of devices per user setting to either 100 or Unlimited.
You can refer to the official documentation here: Manage device identities
Please see the screenshot below from my test tenant for reference.
If you're enrolling devices through Microsoft Intune, note that Intune Enrollment device limit restrictions may also apply.
In such cases, refer to the following troubleshooting documentation:
Troubleshoot device enrollment in Intune – Device cap reached
If a user has already reached their device enrollment limit, they won't be able to enroll additional devices until one of the following actions is taken:
- Existing devices are removed, or
- You increase the device limit by setting device restrictions.
To prevent hitting the device cap, ensure that stale or inactive device records are regularly cleaned up.
Alternatively, you can bypass the device enrollment cap by using a Device Enrollment Manager (DEM) account, as outlined in this article: Enroll corporate-owned devices with the Device Enrollment Manager in Microsoft Intune.