Windows 10 anniversary update broke my connection..

I just upgraded my Surface Pro 3 with Windows 10 to the "anniversary update", and then the strangest thing happen.

I have a connection which goes through a MS RDGW(gateway) and this connection stopped working. But I can still access the same server using another RDP software or the built-in in Windows. I can also still connect to other servers where I connect to another RDGW.

The problem seem to be related to this particular RDGW with this particular client (Remote Desktop Manager Free ver 2.6.3.0) I've tried to edit the setting, create a new connection, even uninstalled and reinstalled the program, but nothing helps.