Do you have a test app to share that we can reproduce this problem? We would like to see if this happens during the discovery or happens after connected.
Our Android guy used an Android app called "nRF Connect" to test it independently of our BLE app code.
...but on Android, the connect attempt usually fails. ...
What specific device and Android version do you use when you observed this problem? I've tried nRF Connect on Zebra TC56 and was able to connect to the ZD410 over BLE straight away.
I'm the Android guy referred to previously. I have tested this on the following platforms:
Kindle Fire 7 (Android 5.1.1).
Google Pixel XL (Android 8.1).
Lenovo TB-X103F (Android 6.0).
I initially discovered this when placing our Zebra ZD410 into "Smart Only" mode in the connection parameters and turning off the WiFi. The Zebra Printer Setup app (Android) fails to discover or connect when the connection is forced over BLE (i.e. smart mode).
On a separate note, from nRF Connect I can connect to a printer on all of the platforms listed above fairly regularly when I put the printer into "Smart Only" mode. It seems the problem occurs when both BLE and Classic are enabled for a printer.
Thanks for your help Steven,