Information regarding iPad wireless connectivity to D-Fly or XT SC-MT800 Display Unit for Di2
To use D-Fly or the MT800 display unit to connect to an iPad or other wireless device, there are some hardware requirements that must be met on both the device and the bike. For example, older iPad models that lack the Bluetooth LE chipset will not work. A more recent model with Bluetooth v4.2 or newer is required. As of this writing (October 2016), these current iPad models will work: iPad Air2 / iPad mini3 / iPad mini4 / iPad Pro.
When you connect the iPad to a D-Fly unit or the MT800 display unit, you’ll be prompted to change its default password from 000000. After you do that, you must go into the iPad's settings > Bluetooth section, select that D-Fly transceiver, and “forget” it. If you skip this step, you won’t be able to reconnect to that D Fly unit because it’ll try to reuse a stored password that’s no longer valid. The app itself instructs you to do this, but doesn't tell you why. Now you know why.