# How Router Works

## How Router Works

- [Welcome to {How To}](https://how.router.works/welcome-to-how-to.md): Configuring and Optimizing OutdoorRouters
- [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.
- [Firewall](https://how.router.works/net/firewall.md): The router firewall controls the forward packet streams from incoming network interfaces to outgoing network interfaces.
- [Port Forward](https://how.router.works/net/firewall/port-forward.md)
- [WiFi Hotspot](https://how.router.works/net/wifi.md)
- [WiFi Relay](https://how.router.works/net/wifi/relay.md): A WiFi relay, also known as a WiFi repeater or WiFi extender, is a feature that allows a router to connect to an existing WiFi network and rebroadcast the signal to extend the coverage range.
- [Guest WiFi](https://how.router.works/net/wifi/guest-wifi.md): Enabling a guest WiFi hotspot to provide internet access to guests and add a security layer by keeping guest devices separate from the master network.
- [Parent Control](https://how.router.works/net/wifi/parent-control.md)
- [Traffic Control](https://how.router.works/net/traffic.md)
- [IP and DNS](https://how.router.works/net/traffic/ip-dns.md)
- [SQM QoS](https://how.router.works/net/traffic/sqm-qos.md): With SQM traffic control, you can enable traffic shaping, better mixing (Fair Queueing), active queue length management (AQM), and prioritization on one network interface.
- [Load Balancing](https://how.router.works/net/traffic/load-balancing.md): A dynamic and flexible mechanism to distribute network traffic across multiple internet connections.
- [Intranet Routes](https://how.router.works/net/traffic/intranet-routes.md): Manually configured routing entries in the router's routing table to define where to forward network packets destined for specific IP address ranges or networks.
- [Traversal Cloud](https://how.router.works/remote/traversal-cloud.md): Traversal Cloud is a secure NAT tunnel tool to provide remote control function on the outdoor router.
- [Ezen Cloud](https://how.router.works/remote/ezencloud.md): One Platform to Manage All Your Routers and Linked Devices - With one cloud dashboard reaching your whole routing infrastructure.
- [VPN Tunnel](https://how.router.works/remote/vpn-tunnel.md)
- [ZeroTier](https://how.router.works/remote/vpn-tunnel/zerotier.md): ZeroTier is a software-defined networking (SDN) solution that creates secure virtual networks using encrypted P2P tunnels, without requiring public IP addresses.
- [Tailscale](https://how.router.works/remote/vpn-tunnel/tailscale.md): Tailscale is a VPN solution that provides seamless connectivity between devices across different networks without the need for public IP addresses or complicated firewall rules.
- [Wireguard](https://how.router.works/remote/vpn-tunnel/wireguard.md): WireGuard is a modern, high-performance VPN protocol that establishes secure point-to-point connections using advanced cryptography.
- [Openvpn](https://how.router.works/remote/vpn-tunnel/openvpn.md): OpenVPN  uses SSL/TLS to establish secure, encrypted tunnels. It supports both site-to-site and remote access setups, offering strong security through certificate-based authentication.
- [Dynamic DNS](https://how.router.works/remote/dynamic-dns.md): Dynamic DNS provides a convenient way to access Mobile SIM card routers remotely over the Internet, even when they have a cellular carrier-assigned IP address that changes periodically.
- [SSH Terminal](https://how.router.works/dev/ssh.md): The command-line interface (CLI) means interacting with the router system where the user issues commands to the router system through command lines.
- [VI Editor](https://how.router.works/dev/ssh/vi.md): VI Editor is a powerful and efficient text editor once you become familiar with its commands.
- [Crontab Syntax](https://how.router.works/dev/ssh/cron.md)
- [Command Sets](https://how.router.works/dev/command.md)
- [MMCLI Commands](https://how.router.works/dev/command/mmcli.md)
- [SMS Message](https://how.router.works/dev/command/mmcli/sms-message.md): The mobile modem supports SMS service for sending messages online.
- [Location 3GPP GPS](https://how.router.works/dev/command/mmcli/3gpp-gps.md)
- [AT Commands](https://how.router.works/dev/command/at-5g.md): The mobile modem can be configured by AT commands. Different mobile modems use the different AT commands. Below are the AT commands for 5G modems using on the 5G SIM routers.
- [AT+QAGPIO](https://how.router.works/dev/command/at-5g/at-qagpio.md): AT+QAGPIO is an AT command used in Quectel cellular modules to set the output level of a GPIO pin on the AP or PMU. It can control external devices or sensors connected to the pin.
- [AT+QTEMP](https://how.router.works/dev/command/at-5g/at-qtemp.md): The AT+QTEMP command retrieves the temperature value of the MT (Module Temperature). This command is supported by Quectel cellular modules and allows you to monitor the module's temperature.
- [AT+COPS](https://how.router.works/dev/command/at-5g/at-cops.md): The AT+COPS command allows retrieving information about the current mobile network operators and their status. It facilitates selecting automatic or manual network selection mode.
- [AT+QENG](https://how.router.works/dev/command/at-5g/qeng.md)
- [AT+QCAINFO](https://how.router.works/dev/command/at-5g/qcainfo.md)
- [Bootloader](https://how.router.works/dev/bootloader.md): The Bootloader initializes the hardware and loads the operating system for starting up the router and preparing it to run the firmware system.
- [Custom-Build Firmware](https://how.router.works/dev/custom.md)