Bluetooth mic garbled or won't connect

[mpaine_99]

I have iPhone 7+ running 10.2.1. When using Bluetooth headphones the mic is either terribly garbled or won't connect(FaceTime, phone, voice memos etc.). This behavior is intermittent. Headphones have tried Bose pulse(3 sets), beats wireless 2, beats wireless3, AirPods and plantronics. All have same behavior. So I doubt it's the headphones



Network settings have been reset, all Bluetooth connections removed and only headset added back, device restored from backup, iphone7+ replaced I.e hardware replaced, iphone7+ wiped and set up as new. Any odd apps deleted. No luck.



Any ideas or anyone had this experience.



Kind regards Matt