KB3130: Cannot install Veeam ONE Agent from the Monitor ...
https://www.veeam.com/kb313023.03.2020 · By design, you cannot install Veeam ONE Agent twice on the same server. Check that Veeam ONE server can collect the diagnostic data from the specific Veeam Backup&Replication server. If not, do the following: Make sure that port 2805 is open and all the needed permissions are configured as described in the Deployment Guide. Reinstall Veeam ONE ...