> For the complete documentation index, see [llms.txt](https://how.router.works/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://how.router.works/mobile.md).

# Mobile Modem

- [Switch SIM Card](https://how.router.works/mobile/switch-sim-card.md)
- [Mobile Watchdog](https://how.router.works/mobile/mobile-watchdog.md): \[Exclusive] Mobile internet guardian program and automatically keep mobile modem alive.
- [Mobile Protocol](https://how.router.works/mobile/protocol.md): Mobile protocol enables session management, authentication, and IP connectivity to transport data over high-speed cellular networks.
- [APN Setting](https://how.router.works/mobile/apn.md): Accurate APN settings are crucial for successfully establishing connectivity on a mobile network.
- [Mode & Band Locking](https://how.router.works/mobile/band.md): Locking 4G/5G Router's Modes and Bands
- [Modem Diagnosis](https://how.router.works/mobile/dx.md): Validate mobile connectivity and determine if SIM card, signals, APN settings troubleshooting needed.
- [Change TTL Value](https://how.router.works/mobile/dx/ttl.md): With individual control over the IP packet lifespan per interface, you can optimize TTL best to suit the type of connected devices and usage profiles.
- [Detach Reattach](https://how.router.works/mobile/dx/detach-reattach.md)
- [Fix PLMN Error](https://how.router.works/mobile/dx/plmn-error.md): PLMN is the core identifier for the mobile network that allows cellular devices like modems to identify and connect to specific carrier networks globally correctly.