The "flaky"'ness of your VPN experience is likely not related to the Almond+.
If you are able to connect a device to the VPN on one WiFi network but not a different WiFi network, the WiFi network in question probably has some restrictions (firewall rules) that are creating problem.
In your case, if it works over an Open WiFi but not over Cellular, you may have some data restrictions enabled by default. (possibly roaming data or data saver or something of that ilk)
Similarly, if you can connect with your smartphone but not your laptop, both using the same Wifi network, then the issue is probably not the Almond+ but rather the VPN software on the laptop. An example of this is IOS devices using IOS 9.x have all sorts of issues with IPSec VPN's and have since last fall.
Try setting up a different type of VPN on the A+ and see if that makes a difference.