Why does my Arris modem show connected but no internet?

This 'connected but no internet' state usually means the modem has established a physical link but either: (1) the ISP DHCP server did not assign a public IP — check the modem's WAN IP at 192.168.100.1 and see if it's valid or 0.0.0.0; (2) a DNS failure — test by pinging 8.8.8.8 directly; or (3) a routing/NAT issue after a firmware glitch — a full 30-second power cycle followed by DHCP release/renew on client devices resolves this in most cases.

How do I fix Arris NVG443B or NVG468MQ WiFi not working after an AT&T firmware update?

AT&T firmware pushes to NVG443B and NVG468MQ units can disable the 5 GHz radio or reset wireless settings. Log into http://192.168.1.254 with your admin credentials, navigate to Home Network > Wi-Fi, and manually re-enable both radios. If the radio appears enabled but devices still cannot connect, perform a 5-second soft reset (not factory reset) to restart the wireless subsystem without wiping your configuration. The NVG468MQ also has a known uptime bug requiring periodic reboots — enable scheduled reboots in the Diagnostics menu.

Why is my Arris Surfboard not connecting to the internet after I replaced it?

Cable ISPs provision modems by their MAC address. When you replace a modem, the ISP's CMTS does not automatically recognize the new device. You must call your ISP, provide the new modem's MAC address (on the bottom label), and ask them to provision it. The modem's Online LED will remain off or blink until provisioning is complete. Some ISPs allow self-service modem registration through their website or app.

What do T3 and T4 timeout errors mean in my Arris modem event log?

T3 timeout means the modem sent a ranging request on the upstream channel but received no response from the ISP's Cable Modem Termination System (CMTS). This is almost always a signal quality problem — upstream power too high or too low, high noise on the line, or a bad coax connector. T4 timeout is a more severe version: the modem went through the entire T3 retry cycle without success and reinitializes, causing a connection drop. Check upstream power levels (target 38–48 dBmV) at http://192.168.100.1 and inspect all coax connections and splitters.

My Arris router shows the WiFi SSID but devices cannot get an IP address — how do I fix this?

If clients associate with the WiFi but get a 169.254.x.x address (APIPA), the Arris DHCP server is not responding. First, power cycle the router. If the issue persists, log into the router admin panel and verify DHCP server is enabled under LAN settings with a valid IP pool (e.g., 192.168.0.100 – 192.168.0.200). Also check that the DHCP lease pool is not exhausted — reduce lease time or expand the pool range. As a quick test, manually assign a static IP on one client device in the same subnet as the router's LAN IP to confirm routing still works.

Arris Router Issues: Connected But No Internet, WiFi Not Working & Complete Fix Guide

Fix Arris router issues including no internet, WiFi not working, and modem not connecting. Step-by-step troubleshooting for NVG443B, NVG468MQ, Surfboard & more.

Last updated: February 27, 2026

Last verified: February 27, 2026

2,463 words

Key Takeaways

Root Cause 1: DHCP lease failure or IP conflict — the Arris modem/router obtains an IP from the ISP but fails to propagate a valid gateway, resulting in 'connected but no internet' symptoms visible as 169.254.x.x self-assigned addresses on client devices.
Root Cause 2: Provisioning or signal level issues — downstream/upstream power levels outside acceptable ranges (-7 to +7 dBmV downstream, 38–48 dBmV upstream for DOCSIS 3.0) prevent the cable modem from completing registration with the ISP CMTS, shown as T3/T4 timeout errors in the event log.
Root Cause 3: Firmware bug or corrupted configuration on models NVG443B and NVG468MQ causing WiFi radio to stop broadcasting SSIDs after extended uptime or automatic firmware push from ISP.
Quick Fix Summary: Power-cycle the modem/router (30-second hard reset), check coax signal levels at 192.168.100.1, release/renew DHCP on connected devices, factory reset as last resort, and contact ISP if T3/T4 timeouts persist in the event log.

Fix Approaches Compared
Method	When to Use	Time	Risk
Power Cycle (30-second restart)	First step for any connectivity loss; modem stuck, no sync light	2–5 min	None
DHCP Release/Renew on Client	Client shows 169.254.x.x or wrong subnet; router online but device offline	1 min	None
Check Signal Levels at 192.168.100.1	Intermittent drops, slow speeds, T3/T4 timeouts in event log	5–10 min	None (read-only)
WiFi Radio Toggle / SSID Rebind (NVG443B/NVG468MQ)	WiFi SSID disappeared or not broadcasting after firmware update	5 min	Low — may drop connected clients briefly
Change DNS Servers (8.8.8.8 / 1.1.1.1)	Pages not loading but ping to IP works; DNS resolution failures	3 min	Low
Factory Reset (pinhole reset)	All other steps failed; config corruption suspected	10–15 min	Medium — all settings wiped
ISP Line / Provisioning Call	T3/T4 timeouts persist, signal levels bad after line check, MAC not provisioned	30–60 min	None — ISP-side fix

Understanding Arris Router Issues

Arris manufactures a wide range of gateway devices — from the consumer-grade Surfboard series (SB6183, SB8200) to ISP-deployed combo units like the NVG443B (AT&T) and NVG468MQ (AT&T Fiber/VDSL). While these devices are generally reliable, a cluster of predictable failure modes emerges across all models. Understanding the OSI layer at which your failure is occurring is the fastest path to resolution.

Key symptom buckets:

No internet, all devices: Problem is at the modem/WAN level or ISP.
No internet, one device: Problem is at the client or LAN level.
WiFi not working / SSID missing: Problem is at the wireless radio or SSID config layer.
Intermittent drops: Signal level or firmware instability.

Step 1: Identify Your Failure Layer

Check the front-panel LED pattern first.

LED State	Meaning
Power solid, DS/US blinking	Scanning for signal — coax/ISP issue
All LEDs solid green	Normal operation
Online LED off	Not registered with ISP CMTS
WiFi LED off	Radio disabled in config
2.5G/Link LED amber	Ethernet speed mismatch

Arris Surfboard models (SB6183, SB8200, SBG8300): Navigate to http://192.168.100.1 to access the modem diagnostic page — this is always available even when WAN is down, as long as you are connected via Ethernet.

Arris NVG443B / NVG468MQ: Access the gateway UI at http://192.168.1.254 (default). Default credentials are printed on the device label. Admin credentials are often attadmin / <device password>.

Step 2: Check Signal Levels (Cable Modem Models)

Navigate to http://192.168.100.1/cgi-bin/status_cgi or http://192.168.100.1 and look for the Signal tab.

Acceptable DOCSIS 3.0 ranges:

Downstream Power: -7 to +7 dBmV (ideal: 0 dBmV)
Downstream SNR: >= 33 dB (ideally >= 38 dB)
Upstream Power: 38 to 48 dBmV (DOCSIS 3.0), 38 to 51 dBmV (DOCSIS 3.1)
Corrected/Uncorrectable Errors: Should be near 0 — rising uncorrectables indicate a bad coax connection or line degradation.

If levels are outside range: Check coax connections at the wall plate and modem. Split signals (using a coax splitter) degrade levels by 3.5 dB per port. Bypass any splitters to test. Contact your ISP for a line technician if you cannot correct levels.

Step 3: Check the Event Log for T3/T4 Timeouts

Navigate to http://192.168.100.1/cgi-bin/event_log or the Event Log tab.

Critical error messages to look for:

T3 time-out; - Loss of Signal (LOS)
T4 time-out while trying to range on upstream channel
No Ranging Response received - T3 time-out
CMTS Ranging Received; CM-MAC=xx:xx:xx:xx:xx:xx

T3 timeouts indicate the modem sent a ranging request but received no response from the CMTS — almost always a signal/noise issue on the upstream channel. T4 timeouts (no T3 response within the T4 window) result in the modem re-initializing — causing the connectivity drops users experience.

Step 4: Fix 'Connected But No Internet' on Client Devices

This symptom — where WiFi or Ethernet shows 'connected' but browser says no internet — is caused by one of three sub-issues:

A) DHCP Failure (169.254.x.x self-assigned IP)

Run the commands below on Windows to diagnose and fix:

ipconfig /all
ipconfig /release
ipconfig /renew
netsh winsock reset
netsh int ip reset

On macOS/Linux, run:

ifconfig en0  # or ip addr show
sudo dhclient -r && sudo dhclient

B) DNS Resolution Failure (connected but pages won't load)

Test with a direct IP ping first:

ping 8.8.8.8
curl -I http://93.184.216.34  # example.com IP

If the IP ping works but domain names fail, the problem is DNS. Change your DNS servers to 8.8.8.8 (Google) or 1.1.1.1 (Cloudflare) either on the device or in the Arris gateway LAN settings.

C) Duplicate IP / ARP conflict

Check with:

arp -a
ping -c 4 <your gateway IP>

If you see duplicate MAC entries or the gateway doesn't respond, disable and re-enable your network adapter or reassign a static IP outside the DHCP pool.

Step 5: Fix Arris WiFi Not Working / SSID Missing

NVG443B and NVG468MQ specific steps:

Log into http://192.168.1.254 → Home Network → Wi-Fi.
Verify both 2.4 GHz and 5 GHz radios show Enabled. If disabled, toggle on and Save.
Check that the SSID broadcast is set to Enabled (not hidden).
If the radio toggle appears stuck or greyed out after a firmware update, perform a soft reset: hold the reset button for 5 seconds (soft) vs. 30 seconds (factory).
For the NVG468MQ after AT&T firmware version 9.2.2h0d83, a known bug causes the 5 GHz radio to stop responding to association requests after ~14 days of uptime. Workaround: set a scheduled reboot via the gateway UI under Diagnostics → Reboot Scheduling.

Arris Surfboard WiFi Gateway (SBG8300, SBG10):

Navigate to http://192.168.0.1 → Wireless → Radio Settings.
Verify radio is enabled and channel width is set to Auto (not locked to an incompatible width).
If 5 GHz is invisible on clients, check if the channel is set above 100 — some older client adapters don't scan DFS channels (100–140). Set manually to channel 36 or 40.
Check for wireless interference: set 2.4 GHz to channels 1, 6, or 11 only (non-overlapping).

Step 6: Factory Reset as Last Resort

Before resetting, note your:

WiFi SSID and password
Any port forwarding rules
Static IP assignments
ISP account credentials (if PPPoE)

Factory reset procedure (all Arris models):

Locate the pinhole reset button on the rear panel.
With the device powered ON, insert a pin and hold for 30 seconds.
Release and wait 3–5 minutes for full reinitialize.
Reconfigure via the gateway UI.

After reset, cable modem models may require ISP re-provisioning. Call your ISP support line and provide the modem's MAC address (printed on label) to request a re-provision/refresh signal.

Step 7: When to Call Your ISP

Escalate to your ISP if:

T3/T4 timeouts persist after power cycle and cable inspection.
Signal levels are outside acceptable ranges and you cannot find a physical cause.
The modem's Online LED never becomes solid (modem never registers).
You see the error DHCP FAILED - Discover sent, no offer received in the event log — the ISP DHCP/CMTS is not responding to the modem's provisioning request, which is an ISP-side issue.
The modem MAC address is not recognized by the ISP system (replaced modem needing provisioning).

Frequently Asked Questions

bash

#!/usr/bin/env bash
# Arris Router / Modem Diagnostic Script
# Run on a Linux/macOS client connected to the Arris device
# For Windows, equivalent commands are shown in comments

echo "=== Arris Network Diagnostic Tool ==="
echo "Timestamp: $(date)"
echo ""

# --- 1. Show current IP configuration ---
echo "[1] Current IP Configuration:"
if command -v ip &>/dev/null; then
  ip addr show
else
  ifconfig
fi
# Windows equivalent: ipconfig /all

echo ""

# --- 2. Check default gateway ---
echo "[2] Default Gateway:"
if command -v ip &>/dev/null; then
  ip route show default
else
  netstat -rn | grep default
fi
# Windows equivalent: route print 0.0.0.0

GATEWAY=$(ip route show default 2>/dev/null | awk '/default/ {print $3}' | head -1)
echo "  Detected gateway: $GATEWAY"

echo ""

# --- 3. Ping gateway ---
echo "[3] Pinging default gateway:"
if [ -n "$GATEWAY" ]; then
  ping -c 4 "$GATEWAY"
else
  echo "  No gateway detected — DHCP failure likely"
fi
# Windows equivalent: ping <gateway_ip>

echo ""

# --- 4. Ping ISP DNS (tests WAN routing) ---
echo "[4] Pinging 8.8.8.8 (Google DNS) — tests WAN routing:"
ping -c 4 8.8.8.8
# Windows equivalent: ping 8.8.8.8

echo ""

# --- 5. DNS resolution test ---
echo "[5] DNS Resolution Test:"
if command -v dig &>/dev/null; then
  dig +short google.com A
  echo "  Trying alternate DNS server 1.1.1.1:"
  dig +short @1.1.1.1 google.com A
elif command -v nslookup &>/dev/null; then
  nslookup google.com
  nslookup google.com 1.1.1.1
fi
# Windows equivalent: nslookup google.com && nslookup google.com 1.1.1.1

echo ""

# --- 6. Check Arris modem diagnostic page (cable modem models) ---
echo "[6] Attempting to reach Arris modem diagnostic page (192.168.100.1):"
if command -v curl &>/dev/null; then
  curl -s --max-time 5 -o /dev/null -w "HTTP Status: %{http_code}\n" http://192.168.100.1
else
  echo "  curl not available — manually open http://192.168.100.1 in browser"
fi

echo ""

# --- 7. Check Arris NVG gateway UI ---
echo "[7] Attempting to reach Arris NVG gateway UI (192.168.1.254):"
if command -v curl &>/dev/null; then
  curl -s --max-time 5 -o /dev/null -w "HTTP Status: %{http_code}\n" http://192.168.1.254
fi

echo ""

# --- 8. Traceroute to detect where routing breaks ---
echo "[8] Traceroute to 8.8.8.8 (stops at 15 hops):"
if command -v traceroute &>/dev/null; then
  traceroute -m 15 8.8.8.8
elif command -v tracepath &>/dev/null; then
  tracepath -m 15 8.8.8.8
fi
# Windows equivalent: tracert -h 15 8.8.8.8

echo ""

# --- 9. ARP table (detect duplicate IPs) ---
echo "[9] ARP Table (check for duplicate MACs at gateway IP):"
arp -a
# Windows equivalent: arp -a

echo ""

# --- 10. DHCP renew (Linux) ---
echo "[10] To renew DHCP lease on Linux, run:"
echo "     sudo dhclient -r && sudo dhclient"
echo "     or: sudo systemctl restart NetworkManager"
echo ""
echo "     On macOS: sudo ipconfig set en0 DHCP"
echo "     On Windows: ipconfig /release && ipconfig /renew"
echo "     On Windows (winsock reset): netsh winsock reset && netsh int ip reset"

echo ""
echo "=== Diagnostic Complete ==="
echo "Review output above to identify the failure layer."
echo "Check http://192.168.100.1 Signal tab for cable modem power/SNR levels."
echo "Check http://192.168.100.1 Event Log tab for T3/T4 timeout errors."

Error Medic Editorial

The Error Medic Editorial team is composed of senior DevOps engineers, SREs, and network administrators with 10+ years of experience in ISP infrastructure, home and enterprise networking, and systems troubleshooting. Our guides are grounded in real incident postmortems, manufacturer documentation, and hands-on lab testing. We specialize in translating complex networking failures into clear, actionable remediation steps for both technical and non-technical audiences.

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