Attempting to add Server 2019/Hyper-V 2019 may fail with an access or timeout issue when Veeam is installed on Server 2016/Windows 10.
When attempting to add Hyper-V 2019:
Error Failed to connect to host 192.168.1.26 Error Access denied or timeout expired. Error Check if you have local administrator privileges on computer '192.168.1.26'. Error Possible reasons: Error 1. Invalid credentials. Error 2. Specified host is not a Hyper-V server. (System.Exception)
Veeam B&R 126.96.36.1999 Adds support for Server 2019/Hyper-V 2019. However, there is a known issue with RemoteWMI on Build 1803 of Windows 10/Server 2016.