Answer | If all the client devices in the home network have lost Internet connectivity, troubleshooting may resolve or provide insight on the cause of the issue.  This document provides helpful troubleshooting steps for Internet connectivity issues with the G18/G20.
Troubleshooting on the G18/G20 is not needed if the following scenarios are applicable:
- First Time Setup
For first-time installation of the G18/G20Â in a home network, follow the installation steps in article #Â 19604Â - G18/G20: First Time Installation.
 - At Least One Client Device with Internet Access
The G18/G20Â is connected to the Internet if at least one client device in the home network can access the Internet. Â Connect the clients without Internet access to the G18/G20Â with an Ethernet cable or to the Wi-Fi network. Â Additional troubleshooting may be needed on the client without the Internet.
The following troubleshooting steps are to be followed in sequence:
- Check the Power Supply
- Check the Gateways LED Light Status
- Power Cycle the Gateway
- Check the Cable Signal levels
- Reset to Factory DefaultsÂ
Check the Power SupplyUse the power supply included with the G18/G20.  Overall functionality and performance cannot be guaranteed if the incorrect power supply is used when installing the G18/G20.  When using the incorrect power supply, the G18/G20 may get online and function, but firmware upgrades will not be completed successfully.  Check the Gateways LED Light Status
The first step in troubleshooting is to check the LED located on the front of the G18/G20. Â Reference the table below to identify the possible issue for the LED status and perform the steps listed under Possible Solutions. Â The detailed troubleshooting steps for the power cycle, check cable signal levels, and reset to factory defaults are available below the LED Light Status table. Â
| LED Status | Possible Issues | Possible Solutions | | OFF | The Wi-Fi cable modem is not properly plugged into the electrical wall outlet |
- Check for damages on the power cord.
- Connect the power cord from the gateway to an electrical outlet.
- Check that the electrical outlet is working; if controlled by a wall switch, confirm the wall switch is on.
- Try a different electrical outlet.
| GREEN
BLINKING | IP registration is unsuccessful |
- Check each end of the coaxial cable connection of the Wi-Fi cable modem and cable wall outlet. Use your hand to tighten each connector, if necessary.
- Check the Ethernet cable (if connected) to make sure it is properly connected to your Wi-Fi cable modem and computer.
- If you have cable television service, check your television to ensure your cable service is operating properly.
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Power Cycle the Gateway
Power cycling the gateway is one of the easiest troubleshooting methods that may resolve connectivity issues. Â It allows the G18/G20 to re-establish connection while retaining its current configuration settings. Following the steps below to power cycle the G18/G20.
- Shut down the computer and switch off any connected clients.
 - Disconnect the power cord from the AC wall outlet and wait one minute.
 - Connect the power cord to the wall outlet.
 - Wait until the LED is solid Green (Online in DOCSIS 3.0 mode) or Blue (Online in DOCSIS 3.1 mode).
NOTE:Â The G18/G20Â Gateway takes approximately 4Â minutes to fully operate after reboot.
- Restart the computer and client devices to check if the Internet connection is working.
Check the Cable Signal LevelsAll DOCSIS cable modems require that the cable signals fall within a very specific range to be an acceptable level for the gateway to connect to the Internet.  The Downstream Power, Downstream SNR (Signal to Noise Ratio), and Upstream Power levels must be within the acceptable ranges for the G18/G20 gateway to operate properly.
- Launch a web browser, such as Internet Explorer, Firefox, or Safari. Enter http://192.168.0.1 into the address box, and press the Enter key. The https:// Redirect page will appear. Â
 - The SURFboard Web Manager is redirecting to a more secure connection, click the Proceed button to continue.  The Gateway > Login page will appear.
 - A security or private risk alert may appear on the web browser advising users to proceed with caution when accessing the Web Manager. There is no risk in proceeding to the Web Manager. For instructions to bypass the alert screen, refer to article # 18181 - Alert Message for Web Manager Access.
NOTE: The Home Network Wizard will appear if this is the first time accessing the Web Manager. For assistance with the wizard, refer to article # 19602 - G18/G20: Web Manager First Time Login.
 - The Username field has admin populated,  enter the custom password in the Password field.
NOTE: If the Login page prompts for an email address and password, retrieve the email address and password in the app to sign in. For detailed instructions in the app, refer to article # 19069 - SURFboard Central: Web Manager Access.
 - Click the Login button.  The Gateway > Summary page will appear.
 - On the left-hand menu, click the Connection tab, then click the WAN link on the sub-menu.  The Gateway > Connection > WAN page will appear.
 - In the Downstream QAM section, verify Power Levels (dBmV) are within the acceptable range of -15 dBmV to +15 dBmV for each downstream channel. Click the > next icon to review and capture all the downstream channels.Â
 - In the Downstream QAM section, identify the Modulation and Power Level (dBmV) to verify SNR (dB) levels are within the acceptable range for each downstream channel. Click the > next icon to review and capture all the downstream channels.Â
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| Downstream Signal To Noise Ratio (SNR) | | Modulation | Down Stream Power | Acceptable Downstream SNR | | QAM64 | -15 dBmV to +15 dBmV | +23.5 dB or greater | | QAM256 | -6 dBmV to +15 dBmv | +30 dB or greater | | -15 dBmV to -6 dBmV | +33 dB or greater |
 - In the Upstream QAM section, identify the number of Index and Symbolic Rate (KSym/sec) to verify the Power Level (dBmV) is within the acceptable range for each upstream channel.
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| Upstream Transmit Power Level | | Index | Symbol Rate | Acceptable Upstream Power Levels | Single
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 | 1280 Ksym/sec | 45 dBmV to 61 dBmV | | 2560 Ksym/sec | 45 dBmV to 58 dBmV | | 5120 Ksym/sec | 45 dBmV to 57 dBmV | | Two | 1280 Ksym/sec | 45 dBmV to 58 dBmV | | 2560 Ksym/sec | 45 dBmV to 55 dBmV | | 5120 Ksym/sec | 45 dBmV to 54 dBmV | | Three or more | 1280 Ksym/sec | 45 dBmV to 55 dBmV | | 2560 Ksym/sec | 45 dBmV to 52 dBmV | | 5120 Ksym/sec | 45 dBmV to 51 dBmV |
 - Refresh the page at least twice to identify variations in SNR, Downstream Power, and Upstream Power.
NOTE: If either of the signal levels is outside of the acceptable range, power cycle or factory reset the Wi-Fi cable modem. Factory resetting the Wi-Fi cable modem will eliminate any customized settings.
 - Contact the cable provider to adjust the signal levels to the acceptable level range.
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Reset to Factory Defaults
Resetting the G18/G20 to the factory default settings should be used as the last resort. Â This troubleshooting method resets all of the settings to the factory default state, clearing all previous connectivity configurations set by the cable provider and erasing all custom configurations set by the user. Â
- Carefully insert a paper clip or small object into the reset button and press it.
 - Hold down the Reset button for at least 20 seconds and release it. The G18/G20 will then reboot, once the LED flashes the G18/G20 has finished rebooting and will be configured with the default settings.
NOTE: The G18/G20Â Gateway takes approximately 4Â minutes to fully operate after reboot.
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