Two closely related cellular questions come up constantly: how to set a custom APN, and how to make a dual-SIM device fail over from one SIM to another. This article covers both on Peplink/Pepwave cellular devices.
Setting the APN
The APN (Access Point Name) tells the cellular network which gateway your data should use. Most consumer SIMs are detected automatically, but you'll need to set the APN manually for private APNs, many IoT/MVNO plans, and some business plans.
- In the device web admin, open the cellular WAN's Details / Cellular Settings.
- Set APN to Custom and enter the exact APN string your carrier provided.
- Enter username, password, and authentication type only if your carrier specifies them (most don't).
- Save and let the modem re-register. Confirm you get an IP on that cellular WAN.
APN settings are per-SIM, so a device with two SIMs can hold a different APN for each.
Setting up SIM failover
On a dual-SIM device you can have the router fall back to the second SIM when the first loses service. The key is that the modem can only use one SIM at a time, so this is failover, not simultaneous use of both SIMs.
- Insert both SIMs and confirm each one connects on its own first (set each SIM's APN as above).
- In the cellular WAN settings, enable use of both SIM slots and set the SIM priority (which one is primary):
Tip: You can set SIMs at the same priority! This ensures your device doesn't fall back after a successful failover, reducing churn on your network.
- Set the failover triggers: the device can switch on loss of signal/registration, and you can add a WAN health check (ping or DNS) so it fails over when data stops passing even if the modem still shows "connected."
- Optionally set data-usage limits so the device switches SIMs when a plan's cap is reached.
Tips
- If failover "isn't working," the usual cause is a missing custom APN on the backup SIM, so it connects to the modem but never gets data. Verify each SIM independently.
- For true simultaneous use of two cellular carriers at once (not just failover), you need a device with two modems, then bond them with SpeedFusion.
- These settings can be standardized across a fleet in InControl2 rather than configured device by device.
Need help matching SIMs, plans, and hardware for a deployment? Llama Networks sells mobility plans and Peplink hardware. Reach out to sales[at]llamanetworks[dot]com.