BIGIP VE on Google Cloud: Curl returns 404 - Public URI path not registered

Been scratching my head on this problem for some time now. To avoid testing on our physical production appliances, I recently deployed a BIGIP VE on Google Cloud. When I tried to test the REST API via some simple curl calls, I am getting the following:

curl -sku admin:admin https://vm-external-ip:8443/mgmt/tm/sys/software/volume
{"code":404,"message":"Public URI path not registered:/tm/sys/software/volume","referer":"xx.xx.xx.xx","restOperationId":6004830,"kind":":resterrorresponse"}

When running the same call on our existing physical appliance, it works as expected:

curl -sku admin:admin https://appliance-ip/mgmt/tm/sys/software/volume
{"kind":"tm:sys:software:volume:volumecollectionstate","selfLink":"https://localhost/mgmt/tm/sys/software/volume?ver=12.1.2","items":[{"kind":"tm:sys:software:volume:volumestate","name":"HD1.1",......}

Has anyone experienced this before? If so, is there something different with the deployment on the cloud which I missed out on?

Thanks in advance!