This message was posted on behalf of Intel Corporation
Thanks for reaching out!
We tried to replicate the behavior you described and we were not able to do so. We are using the latest image (201606081705) with BlueZ version 5.22. The following is a screenshot of the test we tried:
As you can see, we let the phone wait for eight minutes before sending a new message and we were able to send the messages without any issues. My best suggestion is that you check your phone settings and see if there are any power-saving feature that will disconnect your phone after a certain amount of time if there is no activity.
Let us know if there are any news.