Please provide more details of the setup.
Is it in fact a RAK2287, or some other spin based on the Semtech design.
What is the host system, and how is it connected? What have you done for select and reset signals?
Does the SX1302 code have test routines the way the SX1301 code does? If so you should try those first; they may not all work but some should.
Also is your gateway configuration correct for the actual gateway build? In the SX1301 there were choices for the clock master radio, something like that may be the case here, too.
If it’s RAK’s card, can you try it on a pi with RAK’s wiring noand RAK’s software?
What are you doing for power supply? Have you checked for brownout at startup?