Peripheral always state connecting and never connect after upgrading to IOS 11

Question

I am using CoreBluetooth for IOS app, after upgrading IOS version the central manager can´t connect to peripheral and not showing any error. Before starting te process to connect I receive this values from the device:

CBPeripheral: 0x1c0106e40, identifier = BE2B06BF-F385-82AC-95E6-65EA1CF8B11F, name = icomon, state = disconnected

and after I try to connect to the device the state changes:

CBPeripheral: 0x1c411bea0, identifier = BE2B06BF-F385-82AC-95E6-65EA1CF8B11F, name = icomon, state = connecting

and nothing more, nothing happen next, I do not receive any data from the central manager and the device state never change.

Answer 1

I was struggling with a problem that has the exact same symptoms. Hopefully it is the same problem, and this response is helpful.

In my case, the problem was caused by a link layer control PDU that my device was sending immediately after the connection was established. Specifically, I am running Apache Mynewt (http://mynewt.apache.org/), and its NimBLE controller initiates the Feature Exchange Procedure immediately after a connection is made. Since my device is the peripheral, while the iOS 11 device is the central, my device sends the LL_SLAVE_FEATURE_REQ PDU.

I don't know if it is the timing involved or the PDU itself, but whatever the case, the iOS device never sends any application-layer data after the feature exchange. When I change NimBLE so that it does not initiate the feature exchange, device interrogation happens normally, and the CoreBluetooth connected callback gets called.