Discovery issues with XB3 on 802.15.4

Hello,
I have been having an issue with my XB3 setup. I have one ( A ) connected to my desktop, the other ( B ) is soldered to a PCB for use in an embedded system.

I am able to view messages sent from A to B on the serial output of the PCB, which would suggest that the 2 XBees can “talk” However I am unable to use the discover node feature to find Xbee B. This is an issue as I wish to update the firmware through OTA.
Thanks

Try enabling API mode on your PC node.

Hi Mvut,
I have done this, but still no progress.
Thanks for the suggestion though