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NETGEAR Nighthawk CAX80 cable modem router troubleshooting

NETGEAR Nighthawk CAX80 cable modem router (CAX80): modem and Wi-Fi (from NETGEAR); ports; provider fit; activation, and a fix for each symptom below.

Modem and Wi-Fi (from NETGEAR)
A DOCSIS 3.1 cable modem with 32 x 8 channel bonding and a dual-band AX6000 Wi-Fi 6 router in one unit, rated for cable plans up to 2 Gbps.

No internetWi-Fi dropsSlow Wi-FiDead zonesDevice won't connectSetup

Part of NETGEAR network model troubleshooting

Reviewed records

2 exact answers

Diagnose the exact device problem

NETGEAR · slow Wi-Fi

NETGEAR Nighthawk CAX80 cable modem router internet or Wi-Fi is slow

Open record NETGEAR · double NAT

NETGEAR Nighthawk CAX80 cable modem router shows double NAT or strict NAT

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Confirm the model first

Which units this covers, and how to tell yours is one of them

Model numbers and patterns: CAX80

Published specification

What is true of this model and changes how you fix it

Official specifications
AX6000 class Wi-Fi 6, up to 6Gbps combined for up to 30 devices. DOCSIS 3.1 modem side rated up to 10Gbps download / 1Gbps upload (actual throughput capped by the subscribed cable plan). 1.5GHz dual-core processor, 4 Gigabit LAN ports plus one 2.5G Multi-Gig port, one USB 3.0 port.
Cable MODEM-ROUTER combo (DOCSIS 3.1 + Wi-Fi 6)
This is a combined cable MODEM and Wi-Fi 6 router in one — it plugs into the coax line and replaces the cable company's rented modem AND router. So 'no internet' can be the DOCSIS/cable side (provider provisioning, coax signal) as well as the router side, and it must be activated with your cable provider.
Provider activation required
A new CAX80 must be registered/activated with the cable provider (they link its identifiers to your account) before it gets internet — a very common 'new modem, no internet' cause. The coax signal lights must be solid.
Wi-Fi 6 dual-band
2.4/5 GHz Wi-Fi 6 (no 6 GHz). Managed by the Nighthawk app or web admin.
Ports
A 2.5 GbE WAN/LAN port, four Gigabit LAN ports and one USB port.
Provider fit
It works with Xfinity, Spectrum and Cox, but does not support cable providers' home phone services.
Activation
On Xfinity, opening a browser after connecting the CAX80 usually redirects straight to Xfinity's own self-activation page; NETGEAR's own install guide covers what to do if that redirect does not happen.

Where these figures were read. netgear.com/home/wifi/modem-routers/cax80/ (Nighthawk CAX80 – DOCSIS 3.1 Cable Modem Router with WiFi 6)

Manufacturer support for this product line. NETGEAR Support — Home networking support. Official NETGEAR router, Orbi, modem, switch and extender support.

Also read for this model. NETGEAR — Nighthawk CAX80 cable modem router; Micro Center — NETGEAR Nighthawk CAX80.

Exact questions

Questions that only have an answer for the NETGEAR Nighthawk CAX80 cable modem router

My new Netgear CAX80 has no internet.+

Because it is a combined cable modem and router, the CAX80 must be activated with your cable provider — they have to register its modem identifiers to your account before it will get service, and skipping this is the top cause of 'new device, no internet'. Call the provider (or use their self-activation) with the modem's details. Also confirm the coax cable is tight and the modem's downstream/upstream and online lights go solid; a light that will not lock is a cable-signal/provisioning issue on the provider side.