I don't have a solution other than trying to downgrade firmwares. You can search this Thread for RTSP since I know others had this problem, but it seemed to be awhile back.
I remember my DB would lose AP connections after power outages. Not all the time but I had to power off the DB, turning off the breaker, then power it back on and then all was good. Also had to do this when the SD-Card got full and no longer was recording to it. I would also pull the card and reformat it...
So try a power down and back on. If that does not work, you may want to try a 2 hour or more power down so the battery of the DB is no longer. 24 hour power Off may be better...