Decided to give StellarMate another try on Rpi 4 with a fresh install of 1.5.1.
Using the iPad app, I get an error when attempting to access the desktop. The iPad app is version 1.9.13. I think I heard there is a newer iOS app, but my version is the latest on the App Store. The error occurs both when I am connected to the hotspot and when connected to my home WiFi.
Attached is a screen shot of the error. I had the same issue that prevented me from using 1.4.6. I have cleared the browser cache on my iPad, as suggested on the Facebook group.