RAK7391 + RAK8213 (EG95-NA) — Dual SIM Not Detected (sim-missing)
Hardware Setup
| Component | Details |
|---|---|
| Gateway | RAK7391 running RakPiOS |
| Cellular Modules | 2x RAK8213 (Quectel EG95-NA, firmware EG95NAFBR05A04M4G) |
| SIM Cards | 2x Soracom IoT SIM Cards (one per RAK8213 Ver B module) |
| SIM Location | Inserted into SIM slots on RAK8213 modules directly |
| SIM Verified | Both SIMs confirmed working in a physical mobile phone |
Problem Statement
Both modems report sim-missing in ModemManager. Neither SIM is detected at the hardware level despite being physically inserted.
Troubleshooting Steps Completed
Step 1 — ModemManager Enumeration
Both modems enumerate correctly via mmcli -L:
/org/freedesktop/ModemManager1/Modem/0 [QUALCOMM INCORPORATED] QUECTEL Mobile Broadband Module /org/freedesktop/ModemManager1/Modem/1 [QUALCOMM INCORPORATED] QUECTEL Mobile Broadband Module
Step 2 — AT Command SIM Status Check
Queried both modems directly via ttyUSB2 and ttyUSB8:
AT+QSIMSTAT? +QSIMSTAT: 1,0
Result: SIM not detected at modem firmware level on both modems.
Step 3 — Discovered SIM Detection Was Disabled
Found AT+QSIMDET disabled by default on both modems:
AT+QSIMDET? +QSIMDET: 0,0
Both modems had SIM detection completely disabled out of the box. Enabled on both and saved to NVRAM:
AT+QSIMDET=1,0 AT+CFUN=1,1
Verified setting persisted after modem reset:
AT+QSIMDET? +QSIMDET: 1,0
Step 4 — QMI Level SIM Slot Status Check
Queried both modems via qmicli:
sudo qmicli -d /dev/cdc-wdm0 --uim-get-slot-status sudo qmicli -d /dev/cdc-wdm1 --uim-get-slot-status
Result on both modems:
Physical slot 1: Card status: absent, Slot status: active Physical slot 2: Card status: absent, Slot status: inactive
Step 5 — QMI SIM Power Cycle
Power cycled SIM slots via qmicli on both modems:
sudo qmicli -d /dev/cdc-wdm0 --uim-sim-power-off=1 sudo qmicli -d /dev/cdc-wdm0 --uim-sim-power-on=1
After power cycle, card status changed from absent to:
Slot [1]: Card state: 'error: no-atr-received (3)'
This confirms both SIMs are physically present and the modem can sense voltage — but the I/O data pin is not making reliable contact so the SIMs cannot complete their ATR (Answer-To-Reset) initialization.
Step 6 — Rapid Power Cycling (5 attempts)
Repeated SIM power cycle 5 times on both modems — consistent result each time:
Card state: 'error: no-atr-received (3)'
Step 7 — Dual Modem Conflict Test
Unbound modem 1 from qmi_wwan driver to test modem 0 in isolation:
echo -n "1-1.3:1.4" | sudo tee /sys/bus/usb/drivers/qmi_wwan/unbind
Result: modem 0 still returned no-atr-received in isolation. Dual modem conflict ruled out as cause.
Step 8 — USB Driver Unbind/Rebind
Unbound and rebound both modems at USB driver level. No change in SIM detection status.
Step 9 — Multiple Full Reboots
Performed multiple full board reboots. Consistent result after every reboot:
cdc-wdm0 slot 1: error: no-atr-received (3) cdc-wdm1 slot 1: absent
Final Status
| Test | Result |
|---|---|
| Both modems enumerate correctly | Yes |
| SIM detection enabled and persisted | Yes |
| Dual modem conflict | Ruled out |
| SIM physically present (voltage sensed) | Yes — no-atr-received confirms this |
| SIM I/O data pin contact | Failed on both modems |
| Reproducible across reboots | Yes |
Root cause: SIM I/O data pin not making reliable electrical contact in the RAK8213 Ver B SIM slot. Physical reseating of both SIMs required.
Questions for the Community
- Is AT+QSIMDET=0,0 the default factory setting on EG95-NA? Should enabling this be part of the standard RAK8213 setup guide?
- On RAK7391, which physical SIM slot maps to which mPCIe slot — should SIMs go into the RAK8213 module's own slot or the RAK7391 board slots?
- Are there known issues with the RAK8213 Ver B SIM slot mechanism causing no-atr-received errors?
- Is the RAK8213 Ver B SIM slot push-push or push-pull type?
- Are Soracom IoT SIMs known to work with EG95-NA on RAK8213? Any specific APN or configuration required?
- Any known RakPiOS or ModemManager version issues with dual RAK8213 SIM detection?
Software Versions
| Component | Version |
|---|---|
| ModemManager | mmcli 1.20.4 |
| Modem Firmware | EG95NAFBR05A04M4G |