I solved my issue using the UART directly from the Pins P21(TX) and P22(RX). I’ve also deduped UART 1 and use it to communicate with my peripheral.
To monitor with the REPL I’m using /dev/ttyACM0 (Ubuntu system)
Yes, you can use lte.pppsuspend() to run AT commands, but then please use lte.connect() to re-connect. If you switch modes, you need to attach again first as the modem resets.