This article documents how to perform an Exchange Online connection performance test using Microsoft Support and Recovery Assistant tool. Results of this test may help in troubleshooting performance issues during Exchange services backup or restore in Veeam Backup for Microsoft 365.
After installation, the application will open and present options for which app to troubleshoot. Open it manually if this screen does not appear or if Microsoft Support and Recovery Assistant is already installed.
Select Advanced Diagnostics from the list on the "Which app are you having problems with?" screen.
Select Exchange Online on the "Which Advanced diagnostic would you like to run?" screen.
Select Check Exchange Online network connectivity on the "Select the diagnostic you'd like to run" screen.
Select Yes when asked to confirm if the machine where the tool is running is affected.
Provide account information for any email address that is affected by the performance issues.
After the connectivity test completes, expand the Network connectivity to CDN section.
If there is no packet loss and the download bandwidth speed is significantly greater than the Veeam Backup for Microsoft 365 job processing rate, Exchange API is most likely being throttled.