Probably there is an unavoidable cause for what is happening here, but want to comment anyway just in case can be useful.
When properly configured, VPNs only route through the remote network the traffic to non-public IP's, so if ASR is accessible from Vietnam it should be possible to access it from a Vietnamese IP while keeping the VPN with Australia working. Usually sys admins on the remote side can provide some help to do so, also because they are potentially the firsts to be interested in avoiding as much traffic as possible through their systems, and hence supporting only the private one.