Modem Diagnosis

Validate mobile connectivity and determine if SIM card, signals, APN settings troubleshooting needed.

Here are the systematic troubleshooting procedures for diagnosing mobile internet connectivity.

This article will be updated periodically to reflect the latest cellular technology and firmware upgrades. The troubleshooting steps provided will correspond to the most current firmware version.

Verify Status

To verify the mobile internet connectivity, access the router and check the mobile status.

Firstly, power up the router by connecting the power adapter. Wait 3-5 minutes to fully start up. Connect to the WiFi hotspot or use a LAN cable to connect directly to the router. Type the router's IP address in the browser address bar to access the admin panel.

Then, check the below pages for the mobile connection status.

  • Front Page: Device Check the "Active SIM Slot" and "SIM Status" on the "Device" section of the front status page.

  • Network > Interface Locate the "Mobile" interface and check the Rx/Tx data stream and IPv4 address.

If the Device status is "Connected" and Mobile obtained an IPv4 address, go to the "Network > Diagnostics" section and use the Ping tool to ping a popular website or public IP address, like, to test basic internet connectivity.

If ping tests fail and the router cannot reach public internet, continue the below troubleshooting steps.

If the Device status is "Not Connected" and there is no IPv4 on the Mobile interface, the router is not obtaining mobile data connectivity correctly.

Then, continue with the next troubleshooting steps.


Several common factors usually cause SIM card routers to fail to connect to the mobile network. Follow the below troubleshooting guide to rule out potential issues.

Signal Quality

Check the signal quality in the area where the router is installed. The mobile modem requires at least -101 dBm to -105 dBm to access the mobile data network. Note: The signal sensitivity can differ depending on different modem models.

  • Check on Router After logging into the router, check the "RSRP" value on the "Device" section of the front page. Note: Depending on the carrier policy, it may not show signal strength when the SIM is unregistered.

  • Check on Phone Use a smartphone with the same carrier SIM and check the mobile signal bars and network type. -101 dBm is about 2 bars on a smartphone.

  • Signal Test Tutorial

    To accurately validate mobile signal strength, refer to this πŸ”—Signal Test Tutorial, and use a signal testing APP or enter field test mode to check the RSRP value.

If the mobile network is 4G-LTE or 5G-NR and the mobile signal is more than 2 bars (or RSRP value is stronger than -101 dBm), continue to the next step to verify SIM card and APN settings.

If receiving 2G or 3G network, or the signal strength is lower than -101 dBm RSRP or fewer than 2 signal bars, insufficient mobile signal could be the cause of connectivity problems.

First, try relocating the router closer to a window or an open space with fewer barriers, especially without metal roof, on a higher point on the pole, and away from other RF antennas and high voltage electrical wires. Then, retest the signal measurements to check if signal has increased.

If still does not resolve poor signal issues, consider upgrading the mobile antennas with a high-gain outdoor external antennas, which can help concentrate distant mobile signals.

SIM Card

  • Verify the SIM card is properly activated and has an active plan with sufficient data allowance. Note: Many issues stem from inactive SIM cards or reaching monthly data limits.

  • Make sure the SIM card is inserted into the SIM1 slot or whichever slot is set as the "Active SIM" in the Mobile settings. By default, the router uses the primary SIM card in the SIM1 slot.

  • Only insert or swap SIM cards while the router is powered off. If you insert a SIM with the router on, reboot the router to detect the SIM card properly.

  • Inspect the SIM card for damage or scratches on the golden contact pins. A damaged SIM can cause intermittent connectivity problems.

  • PIN Code - If a custom PIN is set for your SIM, enter this exact PIN string on the Mobile interface. If the SIM has no PIN enabled or has a default PIN, leave the PIN field blank.

  • Unlimited Data Plan - If your SIM card has an unlimited data plan, please verify with your provider whether the plan allows use in a SIM router for shared connections. Many unlimited plans restrict usage solely to mobile devices like phones and tablets. If your unlimited plan does not permit router use, please consider upgrading to one that supports SIM router connectivity.

  • Bound SIM Card - If your SIM card was provided with a carrier-branded mobile modem, it may be locked to only work with that specific device, even if a different manufacturer makes the modem. Such a SIM likely cannot be used in a third-party router. In this situation, contact your SIM provider to try to unlock the SIM card. If it cannot be unlocked, please obtain a compatible SIM card and data plan to use with your router.

APN Setting

Configuring proper APN (Access Point Name) settings is vital for the router to authenticate and connect to the carrier mobile network. While the router firmware attempts to auto-configure these parameters for major providers, some carriers may require entering customized APN profiles.

First, verify the APN details by consulting your mobile network operator. Ask them for the complete APN credentials, including APN address, username, password, and authorization type.

Then, refer to the APN Setting Tutorial to set up APN parameters. After setting APN, it takes a few seconds to redial. Suggest rebooting the router to ensure the new settings take effect.

Mobile Protocol

The default mobile modem protocol is "Mobile-Data," which automatically selects the most suitable protocols based on the mobile network. The default protocols may not be supported in rural areas with limited cell tower availability or when using some Virtual Network Operators' (VNO) SIM cards. Refer to the Mobile Protocol Tutorial to change to the traditional PPP protocol.

Hard Reboot

If the Mobile interface persists with an error like β€œModem Device Not Present," the internal mobile modem might fail to initialize correctly. It often stems from an interruption when first attempting to register the SIM card on boot up. It can also indicate a hardware defect.

Please try a hard reboot by unplugging the power adapter and leaving it down for 60 seconds before replugging it. It forces a fresh modem initialization sequence and new network registration rather than relying on cached data.

Revert Settings

If the mobile internet worked properly previously but suddenly stopped working after modifying configurations, the new settings most likely have interference issues.

First, methodically revert any new adjustments made before the connection dropout. After rolling back recent changes, reboot the router to reinitialize all services with the confirmed working configuration.

If mobile connectivity fails to restore and reverting alone cannot revert problems, perform a factory reset to wipe all customizations and restart from default factory settings.

Further Debugging

If the troubleshooting steps above do not resolve your mobile connection issue, please gather the information below and email it to us for further debugging:

  • Homepage - Device Section After logging into the router, take a screenshot of the "Device" section on the right side of the homepage.

  • Complete System Log Navigate to "Status > System Log" and copy the router's system log (green background section) to a *.txt or *.doc file.

  • Mobile Interface Status Take a screenshot of the Mobile interface status under "Network > Interface > Mobile."

The above-mentioned information is crucial for troubleshooting mobile connectivity. While the device status and mobile interface provide basic status and error, the timestamped system log is essential for diagnosing connectivity over time.

Please include all three information sources when reporting issues. Together, they give a complete picture needed to trace and debug connectivity problems.

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