QNAP VPN setup question

Hi

Have just started to set up a QNAP 251+ NAS - first time so lots of fun. I am trying to get a VPN set up to browse folders on the NAS via my Android phone.

I have discovered that my LG G2 (lollipop) won't work using the android IPsec VPN (phone resets when I try and make a connection) so I am using OpenVPN.

I have managed to get the OpenVPN to connect from the phone to the NAS direrctly and can see the shared folders, but cannot open these folders (eg multimedia, public etc).

I am using ES file explorer to view the folders on the phone.

Any thoughts on what may be the issue or where I should be looking - any googled suggestions I have tried are not helping.

Cheers