# 4 Advanced

- [4.1 Internet & IP](/manual/4-advanced/internet-ip.md): Run a first quick Internet access test to check Internet connectivity.
- [Changing Web Port](/manual/4-advanced/internet-ip/changing-web-port.md): Guidance of how to change the Web GUI interface port on the EZR23 router.
- [4.2 Firewall Settings](/manual/4-advanced/4.2-firewall-settings.md): The router firewall controls the forward packet streams from incoming network interfaces to outgoing network interfaces.
- [4.3 Dynamic DNS](/manual/4-advanced/4.3-dynamic-dns.md): Dynamic DNS allows that your router can be reached with a fixed hostname while having a dynamically changing IP address.
- [4.4 Traversal Cloud](/manual/4-advanced/4.4-traversal-cloud.md): Traversal Cloud is a secure NAT tunnel tool to provide remote control function on the 4G outdoor routers and connected hosts.
- [4.5 Command-line](/manual/4-advanced/4.5-command-line.md): The command-line interface (CLI) means interacting with the router system where the user issues command to the router system in the form of command lines.
- [4.6 Bootloader](/manual/4-advanced/4.6-bootloader.md): Rescue the EZR24 router from the "brick" mode.