Greetings,
we developed a custom board with a NRF9160 last year to be used with NB-IoT (LTE-M as Fallback) to communicate over HTTPS with our Servers. Now this worked quite well and without any problems, every LTE Connection built up and established in under 10 seconds.
Now with the change from the NRF9160 to the NRF9151 we adjusted the Driver to what was written as changes in the new Documentation (new RX/TX length of modem, UICR, internal Clock, CFUN=1 after config,...). We are using the embassy-net-nrf91 Rust driver. But the NRF9151 does not get any connection to any LTE provider. We can clearly communicate fully with the modem and also get all information from the Sim-Card (no eSim) and do all AT-Commands with correct/possible Responses. The NRF9160-Board still works with the new firmware but not the NRF9151, and it takes now about 30 seconds to establish a connection.
Now the question is: What has to be changed for the driver or hardware to get the new Board with the NRF9151 working as this is the only hardware changed in the whole process? Are there changes in the LTE-Provider-Call setup or similar?
You can take a look at the patched Rust driver at https://github.com/embassy-rs/embassy/pull/4098 (currently dirty PR, needs rebase cleaned). The driver is based on the nrf_modem_lib.c et.al.
Edit: working on Ubuntu Linux 24.04.2 LTS with VSCodium 192.2, rustup 1.28.1, rustc 1.85.1, embassy at 141c170d + Patch