I think in order to control your Sonos system remotely, you need to be a subscriber to Sonos Pro. The rest of us need to be on the same subnet (although Spotify has Spotify Connect, which you could use after the first session, as long as no one breaks the connection…)

Would a remote connection like a VPN work?

 Hi Yes Im using a VPN with remote desktop to control. I suppose its a more invisible approach to control probably development of the SONOS app. 

We have staff and I would like to use IOS ie my phone to remotely control the music offsite. I cant control what the staff are playing on SONOS there unless I disconnect internet music sources and use local music files. That is my main problem. I do have a Server in my office with SONOS on it, that the staff cannot see but I need to remote to it from another windows computer.

This is a 1st world problem. Ill look at SONOS Pro though

OK Ive looked at SONOS PRO. I wasnt aware of it. This is what I probably need, but it seems it is only available for the US. I am in New Zealand.

I would expect that they may be working out any potential kinks before rolling it out world wide, but you may want to contact Sonos directly to register your desire, and see if my assumptions have any validity. 

Running a Windows Controller and accessing it on a remote desktop removes many of the Sonos networking requirements and it (several of the VNC variants) has worked here for me.

VPN are tricky things, you’d need one that allowed and supported all required Sonos networking needs and it might impact your normal networking. A point to point VPN, your computer to a server on your “Sonos” network, would be your best shot.