IOS11 iFi nano iDSD LE digital output

Hello Apple Community,

Before I upgraded to latest IOS11, my portable DAC iFi nano iDSD LE was working perfectly with all my Apple devices (iPhone 6s & SE and iPad Air 2).

When I try to use my portable DAC now, it is recognized but no sound are playing and after few secondes, portable DAC get ejected.

Any ideas how to resolve it ?

Many thanks for your contribution

Fred