Since the last upgrade the MMI connectivity is very flaky, it displays the tracks but wont play any. The car is fine and the lead has been checked by Audi, it worked perfectly prior to the upgrade. This is an IPhone 6 using the MMIS through the glove box.
iPhone 6, iOS 9.1
I had the exact same problem. Tracks would display and time would indicate the track was playing, but there was no sound. This happened immediately after updating to iOS 9.1 so I suspected an apple software problem. After fiddling with the controls and trying to reset the MMI - didn't really work - music started, right after I hung up with the Audi guy...then it didn't work the next day.
Today I did a hard reset on my iPhone 6 (IOS 9.1) and immediately it worked.
I might say I was streaming via bluetooth to a Viseeo Tune2Air 1000...couldn't hook up my phone directly due to the new plug incompatibility. My older iPad when plugged in worked immediately - before I tried the phone reset. I am sure it's an OS 9.1 issue... I was ready to downgrade to 9.0
I might also say that the quality of music streamed via bluetooth is way below that via a direct plug-in of an older iPhone. I never really compared before the iOS 9.1 change, but the sound quality is noticeable worse via bluetooth now.
Audi MMI Connection
