MG21 Troubleshooting Guide

Troubleshooting connection state issues 

The Local Status Page reports the following connection states for the MG21. 

Troubleshooting no power or no lights issues 

This section covers troubleshooting steps for the MG21 when no lights display after the device powers on.

• Connect the MG21 to a different power source. 
• Use a different Ethernet cable if you are using a PoE injector. 
• Use a different AC adapter, if you are using one. 

Troubleshooting no link light issues

This section covers troubleshooting steps for the MG21 when no link lights display after you connect a device.  

• Check that the RJ45 head is not loose or damaged

• Make sure the connected device is powered on and working

  • Connect the device to another port on the same gateway

  • Connect the device to a switch or some other network cellular gateway

• Swap the Ethernet cable with a cable that is known to work

• Perform a factory reset on the MG21

Troubleshooting sporadic connectivity issues 

If the MG21 has unstable cellular connectivity or a solid amber power LED, the gateway cannot reach the Meraki dashboard. Follow the steps below to diagnose and isolate the issue. 

• With the MG21 turned off, check the SIM card tray and validate the SIM card is properly seated

  • Check the SIM tray cage for damage

  • Check the SIM card alignment if the card is not seated directly

• On external antenna models, inspect the antennas for physical damage, loose connections, or missing antennas. 

  • Improper seated antennas can affect signal quality and prevent the MG21 from forming a stable connection to the cellular tower.

• Confirm the MG is in an optimal location and facing the correct direction. 

  • Point the MG21 toward the desired cellular tower for optimal signal. 

  • Point the MG21 toward the desired cellular tower for optimal signal. The MG21E dipole antennas are designed for omnidirectional gain 

  • Remove physical obstructions that can reduce signal quality. Fresnel zones affect cellular signals the same way they affect Wi-Fi signals 

  • Remove physical obstructions that can reduce signal quality. Fresnel zones affect cellular signals the same way they affect Wi-Fi signals 

• Check the Local Status Page on the MG21 to review signal telemetry and confirm connection quality. 

  • Confirm the signal strength and quality are sufficient. If the modem connection type is 4G or Long-Term Evolution (LTE), the Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) values should be high.   

  • Confirm the band and carrier are correct. Roaming on other carrier networks or using incorrect bands can affect connectivity. 

Troubleshooting cloud connectivity issues 

Use the following checks to determine if the MG21 can communicate with the Meraki dashboard or provide a data connection. 

• Determine if the connectivity issue is due to misconfiguration of the cellular modem in regards to the data plan

  • Check if a PIN is set on the SIM card and if it is locked. If a SIM card PIN has too many failed attempts, a Personal Unlocking Key (PUK) code is required to unlock it

  • Check that the proper bearer configurations are set. Override APN, PIN, username and password, and authentication if required by the carrier

• Confirm with the carrier that the data plan is valid and has an active subscription

• Check data usage and restrictions on the SIM card

• Check that the data plan allows the MG21 to use it. Some carriers restrict data plans by International Mobile Equipment Identity (IMEI)

• Check if the SIM card is paired to the IMEI of another device 

• Moving a SIM card from a previously working device to the MG21 without confirming with the carrier first can lead to troubleshooting the wrong issue. 

• Data plans can be negotiated with the carriers. The data plans provide the quantum of data for uploading/downloading over the network. Post expiry of the data plan, the MG21 cannot communicate to dashboard or provide an active data connection

• Check the cellular uplink IP, connection to internet, and then connection to the cloud

  • Sometimes SIMs will assign an IP but prevent data from passing, preventing internet access

• Leverage an existing network to allow the cellular gateway to check in with Safe Mode

  • Make sure there are no upstream firewalls that could be blocking the cellular gateway's management traffic.

  • Allow the MG21 to check in and update to the latest firmware using Safe Mode

  • If the MG is in Safe Mode and checking into the dashboard, Support can run remote diagnostics to continue troubleshooting

  • If the previous steps do not resolve the issue, perform a factory reset on the device. Refer to the MG21 installation guide for factory reset steps

The MG21 uses 6 to 8 megabytes a day of data for telemetry and connection monitoring on the dashboard when the unit is idle. Additional Cisco Meraki devices added to the MG21 network may increase data usage further. Cisco Meraki devices are cloud-connected and report telemetry to the dashboard for network monitoring.