O365 PowerShell Throttling configuration button does not honor the # of Servers it remains set to 1 even when changed to 10.
This is a bug in the Gui part of the tool the Server setting does not get saved when changed to a number higher than 1.
add key="TenantConcurrency" value="20"
add key="NumberOfMigrationServers" value="5"
add key="MaxPowerShellConnections" value="4"
4). Save and close the file.
5). Start the MNE console.
Please note the GUI will not correctly display the Server number and if you click okay (in the GUI) you will then change the settings back to the incorrect numbers. You you open the ThrottleManager.exe by mistake then just cancel out to avoid implementing the incorrect parameters.
Please note; Microsoft provides a default of Maximum Tenant Concurrency 9. This number they believe is sufficient more most small to medium businesses. Which means the optimal set up would be 3 servers that will perform migrations using MaxPowerShellConnections Setting of 3.
Please see article 107856 for additional information on how these numbers work