I've been using the nRF9160-DK development board for some initial testing of the nRF9160 SiP and as an initial development platform for a custom nRF9160 firmware application. I'm trying to migrate over to a SparkFun Thing Plus - nRF9160 board given its smaller size and external antenna capability, but I'm having issues connecting to the network with this board's nRF9160. I've built and programmed the nRF Connect SDK's AT Client sample to both the nRF9160-DK and the SparkFun Thing Plus as part of my testing, but I've only been successful at connecting with the nRF9160-DK even when using the same SIM card and sequence of AT commands. Both nRF9160 boards are running the same version of modem firmware (v1.3.5), and I've also tried performing a factory reset on both boards using AT%XFACTORYRESET=0 and AT%XFACTORYRESET=1, but the same behavior persists with only the nRF9160-DK connecting to the network.
The SparkFun Thing Plus has a Pulse Electronics W3554B0140 antenna connected whereas the nRF9160-DK has the onboard antenna. We're using the Pulse Electronics antenna with a uBlox modem without any issues. I've also tried using a Yagi antenna that we've used before when network connectivity has been spotty, but I see the same behavior. The SparkFun Thing Plus does appear to find one cell tower but just the one whereas the nRF9160-DK lists 3 after running the AT%COPS=? AT command. And it doesn't seem to matter how long I wait; I've had the SparkFun Thing Plus running for close to an hour with no successful connection while the nRF9160DK connects in under 10 seconds.
Is there something that I'm missing when it comes to getting a new nRF9160 connected to the network?
Here is a screenshot showing the AT command network connect sequence sent to the nRF9160DK:
And here is a screenshot showing the same AT command sequence sent to the SparkFun Thing Plus (note the same modem firmware version, and note that the same SIM card was used):
