Here we have the official 3G fix from Pdaimatejam, it’s a .cab file so you need to use the Cab Sender:
Connect your HD2 to the PC (make sure Zune is not running)
Start the WP7 Update Cab Sender.bat file
On the Command Prompt screen press “S” to send the .cab file to your phone
Wait for the update, the phone will be restarted
Use the Connection Setup app (from HTC) or Network Setup (from Nokia) to set your connection, in most cases there is no need to enter APN, however if you still have problems just manually add the proper APN for your mobile operator.