Today I've a strange behavior of nRF51 DK (everything was working ok until today, the last things I did was to reset the J-link FW after a total erase of the board).
Now, when I upload the Softdevice (S130) and after my Application then I have to press button RESET on nRF51 DK to see my application in the nRF Connect Android ... and once I see it, the connection to my Application in nRF Connect is painful (it fails 75% of times and takes long time when it succeeds).
Do you have any ideas?
Are you using an SDK example or your own custom application? I'm guessing you didn't have to press the RESET button before to see your application in nrf Connect Android when everything was working, right? Would you mind uploading your code so I can test it here and see if I get the same error?
Trying to give you my example, I've found the issue: I had my PC Windows 10 Bluetooth running at the same time as my mobile phone Android!
That's why it was painful, erratic and pressing RESET on nRF51 DK board would somewhat solve it (I'm guessing). The Windows Bluetooth was trying to connect any time (via J-Link) conflicting with my mobile phone Android.
So the rule is to turn off the Bluetooth device on the platform we are developing on .