Hi @Wayne Thank you for reaching out to us, as per the error details shared in the query, we need more details to investigate this like domain name, tenant id and subscription id so that we can check the backend logs for the exact reason for this deployment failure.
Also to view the backend logs for your instance we need to create a case, once you share the subscription id, we can create a free case and review the logs.
Also would recommend to review this article - https://learn.microsoft.com/en-us/azure/active-directory-domain-services/network-considerations Virtual network design considerations and configuration options for Azure Active Directory Domain Services, in the past we have seen similar issue, in those case we did troubleshooting from nsg/virtual network/internet access/deploying vm under the same subnet.
If the above steps doesn't help, you can send us an email on azcommunity [at] microsoft [dot] com referencing this issue with a subject line "ATTN:Givary" we can connect offline to troubleshoot the same.