Required Port 443 For Veeam Backup Replication Is Occupied By Another Application Link

Option D — Use SNI/multiple certificates with HTTP.sys (advanced)

If your Veeam Backup Server is also acting as a Hyper-V host, the native Hyper-V Replica feature natively uses Port 443 to transmit virtual machine replicas. Option D — Use SNI/multiple certificates with HTTP

Port 443 is the default for HTTPS—Veeam needs it for communication between the backup server, proxies, repositories, and the WAN accelerator (especially for Cloud Connect or guest interaction proxies). If something else has claimed that port, your installation won’t proceed. your installation won’t proceed.