Difference between JLink and dev kit for programming boards

[nrbrook]

We have some prototype boards that work fine when programmed via the debug out on the nRF52 dev kit, but have problems when programmed with this JLink. Programming with both by dragging the .hex into the mass storage device drive. Should there be any difference between these?

[Turbo J]

"Real" J-Link adapters can support higher SWDCLK frequencies - which can expose connection or layout problems on SWD.

I recommend using nrfjprog.exe (nrf command line tools) instead. This does not rely on the debugger auto chip detection and you can specify a lower SWD frequency for "bad" wirering.