I’ve read of many issues with BT and iOS 11. Seems the latest update helps, but still issues with premature disconnects..
2016 SV; purchased 20-Jan-17, 13k, 93% SOH; 13-Mar-18
2015 S; purchased 29-July-14, moved to AZ Nov-2014, 22k, 82% SOH; 01-Mar-18
2009 Ford Escape Hybrid 4x2, 110k & going strong!