Go to your folder that has Diablo III: Reaper of Souls installed.
The default for this on a Windows PC is C:\Program Files (x86)\Diablo III

Right click on Diablo III.exe and click ‘create a shortcut’.
Right click on the newly made shortcut and choose ‘properties’.

Go to the Target field, it should say something similar to this:
"C:\Program Files (x86)\Diablo III\Diablo III.exe"

You will need to add one of the commands below after
"C:\Program Files (x86)\Diablo III\Diablo III.exe" in the Target field.

To manually connect to the Australia servers add the line
-launch OnlineService.Matchmaking.ServerPool=AU1
To manually connect to the US servers add the line
-launch OnlineService.Matchmaking.ServerPool=Default


*Note there is a space between Diablo III.exe" and -launch

doesnt working for me either AU1 or default

average latency still the remained same at 250 plus minus