Hello nimi,
Welcome to the MS Q&A forum.
Besides what Andreas Baumgarten already suggested, you need to make sure what you properly prepared a Windows VHD or VHDX to upload to Azure (Windows Firewall rules, remote desktop registry settings, Windows services, Windows configurations for Azure, etc.) and what on-premises machines that you replicate to Azure comply with Azure VM requirements.
Ensuring these modifications are implemented on the image prior the migration/uploading the disk to Azure is crucial. Neglecting proper preparation could result in the Azure VM failing to boot or encountering connectivity issues.
Hope above answers your question and concern. Let me know if you need additional assistance. If the answer was helpful, please accept it and complete the quality survey so that others can find a solution.
Sincerely,
Olga