Accounts of users on the web as well as repeated measurements have shown that the release of iOS 10 has brought a slew of Bluetooth related issues along with it.
We have performed extensive tests with KleverKey's Bluetooth component to determine which versions of iOS suffer from Bluetooth reliability issues. Our measurements have shown noticeable differences between iOS versions before iOS 10.0.2, version iOS 10.0.2 and version iOS 10.1. There appears to be a significant drop in reliability on iOS 10.0.2. Older versions as well as version 10.1 have a much higher reliability than iOS version 10.0.2. Our measurements also showed that on a device running iOS 10.0.2 the reliability varied drastically between device restarts. During our tests, running the tests on iOS 10.0.2 on one day yielded acceptable results. When the same tests were run again on the following day after a fresh device restart, results showed a significant drop in reliability.
Information from Apple
Apple's release notes for iOS version 10.1 corroborate these findings. The release notes for iOS 10.1 state:
"Improves Bluetooth connectivity with 3rd party accessories"
We recommend users with iOS 10.0.2 who are experiencing difficulties with Bluetooth connectivity to upgrade to version 10.1. If an upgrade is not a viable option at the moment, a short-term solution may be to restart the device. This solution, however, may only work temporarily and may not actually improve reliability. Therefore our recommended approach is to upgrade to the next version.