Using your Zyxel C4000LZ modem

Recommended CenturyLink modem

Features of the Zyxel C4000LZ

Secure WiFi compatible
WiFi 6 technology with dual-band 2.4 GHz and 5 GHz 802.11ax
Smart Connect single wireless network (SSID): Auto-selects the fastest band for each device
Single LED status light
Dynamic QoS: Prioritizes data through the router for smoother streaming
Standards-based WiFi WPA3 security

NOTE: This router has the same specifications as the Greenwave C4000LG.

Works with these CenturyLink internet services:

ADSL/ADSL2+/VDSL – single line up to 100 Mbps

Note: Listed speeds reflect the maximum speed the technology can accomodate. In-home speeds may differ based on router setup, devices and other factors.

Diagram of the C4000LZ modem

Modem troubleshooting tips

Did you know? If your internet connection is spotty or slow, the best place to start is rebooting your modem.
Still not running right? Check to see if you need to update the modem's firmware.

Chrome users, right click on the firmware link below and choose "Open link in a new tab."

Download the latest firmware for the C4000LG

Quick setup

Manual network (WAN) setup

If instructed to do so by a technician, you may need to change the WAN settings on your modem manually. Visit the WAN setup page for step-by-step instructions on different WAN configurations, including PPPoE, IPoE and transparent bridging.

Your modem's wireless settings control the WiFi network in your home. This model of router has 2.4 GHz and 5 GHz options for most wireless settings, with exceptions noted below. Click on the options below for details and step-by-step instructions.

Basic settings
Guest wireless setup
Advanced SSID setup
2.4 GHz or 5 GHz WiFi channel setup

Helpful WiFi topics

Important Note: The C4000 is not recommended for use with the G.Hn WiFi/Ethernet Extender Kit and requires manual pairing. If you have a C4000 modem and would like to boost your signal, we recommend ordering a compatible WiFi extender on our Accessories Marketplace.

The modem status area of the user interface allows you to view several options and check how your modem is running.

Connection status
WAN status
Internet status
Ethernet status
Wireless status (find best channel)
View IPv6 address

Firewall status
Device table
NAT table
Routing table
QoS table
Resource table

The utilities menu gives you access to several additional tools to manage and test your modem.

Reboot
Restore defaults
Upgrade firmware
Configuration backup
Web activity log
System log

Time zone
Ping test
Traceroute
Speed test
Diagnostic test
Wireless diagnostics

Advanced settings give you even more control over your modem's configuration. Most of these are best for tech-savvy folks who are familiar with modems and networking.

Blocking & filtering

WAN settings

LAN settings

Remote management

Routing

Security settings

Top Modem/Router Topics

View all Modem/Router topics

Introducing Secure WiFi

Secure WiFi provides automatic cybersecurity for your network and all devices connected to it, plus:

Manage network services
Manage devices
Pause devices
Create groups

Learn More

Introducing WiFi 6

Intel WiFi 6 Gig+ is the next generation in-home WiFi technology, designed for the ever-increasing demand of connected homes and gigabit connections. Compared to WiFi 5, it delivers:

Up to 3x the connectivity speed
Up to 4x the data capacity
Up to 75% less lag time (latency) for gaming and video applications

WiFi 6 also includes embedded cybersecurity, managed network services and parental controls. This feature is available with the Greenwave C4000 modem/router.