Andiodine DNS Tunneling - Connects to server but unable to browse. No internet connectivity

I have an **Iodine** (DNS Tunneling) server running on my VPS and have tested and confirmed DNS Tunneling is working by connecting using the Iodine client from my local Linux machine. When using the **Andiodine** app (https://f-droid.org/packages/org.xapek.andiodine/) on Android however, it connects but i have no internet connectivity. I've done extensive searching and am unable to work out what the issue is.
My Android device is a Nexus 5 running Android version 6.0.1.
Has anyone else experienced this issue? Any remediations or other things to try?