Once you are connected to VyprVPN on the QNAP, you should be able to reach the device itself and any services you have running via the VyprVPN IP address you are assigned. However, this will only work if you have the NAT firewall feature disabled on your account. You can do that from the control panel.
The NAT firewall feature will block all unsolicited inbound requests, so you will not be able to reach the QNAP with it enabled.
If you ensure the NAT firewall is disabled and you're still having trouble reaching the QNAP, please ensure you don't have any firewall restrictions setup on the device itself.
Note: We offer dynamic IP addresses, so your IP will not be fixed. Each time you connect to VyprVPN on the QNAP, your IP address will change. If you need a static IP solution, have a look at VyprVPN Cloud.