On the laptop/ipad all you need is a browser (chrome/firefox/safari) - no other software.

You do need a connection to the machine running OpenVPMS.

Unless you have a static ip address for your practice [which I very much doubt] then you need to use a service like that from dyn.com to get yourself a domain name (eg mypractice.webhop.net) and tell your router to use this "dynamic DNS" service. [For most systems, if your router disconnects and reconnects to the outside world, then your practice's IP address will change, and the 'dynamic DNS' facility handles this because on reconnecting, the router tells Mr Dyn that the practice's IP address has changed to the new one.]

Then the sexy/secure way to do the connection to the office is with a VPN (virtual private network) but these are sometimes difficult to get set up.

The dummer/less secure method is to simply use the 'port mapping' facility in your router.  Pick an 'out of the normal range' port number (eg 53246 - ie something bigger than say 20000 and less than 65000) and map this to port 8080 on the machine running your OpenVPMS system.

From home, you call up http://mypractice.webhop.net:53246/openvpms in your browser and bingo you are talking to OpenVPMS.  it would be wise to have complex passwords - ie not be be able to login as admin/admin.

You dyn.com domain name & DNS service will cost around $US 40/year.

If you do not feel confident to adjust your router, call your friendly neighbourhood geek.

Regards, Tim G