Oh! Sorry, I misunderstood the issue.
Apologies if you already know this, but I just want to make sure: have you checked that the devices you’re using support Bluetooth Low Energy/Bluetooth 4.0? iPad 1 and 2 don’t support BLE, and it looks like the Oppo runs Android 4.2, which doesn’t have BLE support. I don’t know about the dongle though.
Could this be the issue?