Thanks for posting your question in the Microsoft Q&A forum.
Here are steps you can follow to troubleshoot and possibly resolve the issue:
- Verify if there are any ongoing service issues or outages reported by Microsoft for Azure Lab Services. You can check the Azure status page for this information.
- Check the address range settings in your lab account. As mentioned in the search results, insufficient address range can cause issues with lab creation and potentially with registration.
- If you're using a direct registration link, try adding users through the Azure portal instead.
- Ensure that there are no network issues or firewalls blocking access to Azure Lab Services endpoints.
Please don't forget to close up the thread here by upvoting and accept it as an answer if it is helpful