Page content loaded
Did you ever get this fixed? I'm having the exact same problem. Mercedes E Class, iPhone X, bluetooth connects and disconnects continuously. I had no problems with my iPhone 6s. I took my phone to the Genius Bar last night and they couldn't find anything wrong with it. I've reset, turned off Bluetooth, restarted phone, re-paired, etc.
Searching online it looks like many others are having this issue. I wish Apple would acknowledge and work on a fix.
Contact your dealer. This is not an iOS problem, but an issue with the vehicle and its connection with the phone. The vehicle manufacturers get use of the software before it is publicly released so they can test their vehicles with the latest version of Bluetooth and the latest iOS. It is up to them to make sure it works with the phones, not vice versa.
The iPhone X is a different device. Did you set it up with a backup of your iPhone 7 Plus? It could retain connection information from the old phone. Remove the phone listing from the car. Remove the car listing from the phone, then turn Bluetooth off on the phone. You can then go to Settings>General>Reset>Reset Network Settings. Understand this will also clear all wi-fi passwords from the phone as well. Go out to the car and turn the car on and get the system into Discovery/Pairing mode. Open the phone and turn on Bluetooth. Follow the onscreen instructions to complete the pairing process. That is all you can do on the phone side. If it still presents a problem, contact the dealer. It is up to them to determine whether the device is supported with whatever version of iOS is on it.
Question: Issue with Bluetooth in my car iPhone x