Yes, I was running the Lite version previously and am now running the full version.
Here is what failed to connect: I installed the full version. It found the ISY at the proper address and port, but it could not connect until I changed the default connecton method from "Auto" to "Local". I made no change to the value of the Secure connection method (it still had "REMOTE IP" (or whatever the initial value is)).
Just now, however, I tested again by first filling the Secure field in with an invalid URL (google.com) and then filling it in with the correct external URL of my router, and testing both vial WiFi and via cellular data. It now seems to be working properly when set to "Auto", so perhaps the problem was only with the Lite version? Sorry if I was unclear about that in my original post.
To answer your question about my ISY, I'm using version 3.2.6.