On a Quectel modem, a patch might be needed to reliably send AT commands to the modem. This patch comes from the fork lpac-quectel in the file drivers/at.c
We'll also reduce the size of transmissions to the modem to help the modem keep up.
Make the following changes before running make.
Merge the changes in lpac-quectel's at.c into the upstream lpac's at.c. [TODO: provide a patch file or get it pushed upstream]
Edit the file euicc/euicc.c to decrease the size of e10b_mss
ctx->es10x_mss = 60;
Hopefully, in the future these steps will not be necessary.