my husband and I both recently purchased the Z2 with FSA cash at end of year. He uses the nasal cushion mask and has no noise at all. I use the Dreamwear full face mask, I find the noise it not from the machine itself but from the air whipping around in the full face mask and escaping from those pin...

I had the same issue with my new HD Z2, android phone, constantly telling me no device etc. I contacted support. They have a tutorial on how to get it to remember your password and activate the bluetooth connection. Sorry I don't know how to post a link. However in my opinion the APP is not so great...