Troubleshooting an Omada AP That Goes Offline Abnormally

Contents

Objective

Requirements

Introduction

Troubleshooting

Troubleshooting for Wired AP

Troubleshooting for Mesh AP

Conclusion

Objective

This article introduces how to troubleshoot the issues of Omada AP devices going offline abnormally.

Requirements

• Omada AP
• Omada Controller (Software Controller/Hardware Controller/CBC, V5.9 and above)

Introduction

When AP devices go offline (displayed as DISCONNECTED on the Controller), you can refer to the troubleshooting steps in this article.

Troubleshooting

Here are the troubleshooting steps for Wired AP and Mesh AP, respectively.

Troubleshooting for Wired AP

Step 1. Check the LED status of the AP.

• If the LED is off, it indicates that the AP's power supply is abnormal. If a DC power supply powers the AP, check whether the power plug is fully inserted or the power cord is damaged. If PoE powers the AP, check the power sourcing equipment (PSE) and the specifications and length of the Ethernet cable.
• If the LED flashes slowly (e.g., every 5 seconds), it indicates an abnormal connection among the AP, the Controller, and the Gateway. In this case, check whether the Ethernet cable is properly connected and the Controller is correctly configured.

Step 2. Check the AP's IP address to see whether it was changed before it went offline.

• If the AP obtains a static IP address, ensure it is in the same network segment as the Controller’s.
• If the AP obtains a dynamic IP address, go to the DHCP server to check whether the AP has obtained the IP address.

Step 3. Check whether the LAN IP address of the PC where the Controller runs and the IP address of the AP are in the same subnet. If not, check whether Management VLAN has been enabled before the AP goes offline.

• If Management VLAN is enabled, ensure the corresponding VLAN tunnel has been set in the network. Meanwhile, it is also recommended that Option 138 or Option 43 be configured on the DHCP Server based on actual needs.
• If Management VLAN is disabled, check whether the VLAN settings have been modified on the corresponding ports of the DHCP Server. This may lead to a change in the LAN IP address of the PC where the Controller runs. In this case, configure the IP settings to make sure the LAN IP address of the PC and the IP address of the AP are in the same network segment. Then, the controller will be able to manage the AP again.

Step 4. Check whether an IP address conflict occurs in the network. If so, remove the devices with the IP address conflict to see if the offline AP can resume the connection.

Step 5. Check whether the connection between the AP and the Controller is normal. If not, check the Ethernet cable connection.

Step 6. Check whether there are a large number of multicast and broadcast messages in the network that cause abnormal communication between the Controller and the AP and cause the AP to go offline.

Step 7. Check whether the firewall is enabled on the PC where the Controller runs. If it is, abnormal communication between the Controller and the AP may occur.

Step 8. If the AP is an Omada Pro model, check whether the license has expired.

Troubleshooting for Mesh AP

Step 1. Check the LED status of the Mesh AP. If the LED is off, it indicates that the power supply for the Mesh AP is abnormal.

• If a DC power supply powers the AP, check whether the power plug is fully inserted or the power cord is damaged.
• If PoE powers the AP, check the power sourcing equipment (PSE) and the specifications and length of the Ethernet cable.

Step 2. Check whether the Mesh AP supports the same channel of the 5 GHz band as the one set for the Root AP.

Step 3. Ensure that Mesh, Auto Failover, and Full-Sector DFS are all enabled.

Step 4. Check for obstacles that may cause severe signal attenuation, resulting in the Mesh AP going offline.

Step 5. Check whether the transmission power of the Root AP is too low, causing the Mesh AP to go offline.

Step 6. Check the Mesh AP's IP address to see whether it has been changed before it goes offline.

Step 7. Check whether the Management VLAN was enabled before the Mesh AP went offline. If so, ensure the corresponding VLAN tunnel has been set in the network. Meanwhile, it is also recommended that Option 138 or Option 43 be configured on the DHCP Server based on actual needs.

Step 8. Check whether you have ever logged into the standalone Web GUI of the Mesh AP before it was adopted by the Controller. If you have, this may cause the AP to be unable to become Isolated and be discovered and managed by the Controller. In this case, reset the AP to factory defaults and just keep it powered on without any settings.

Conclusion

This article presents the troubleshooting methods to deal with the abnormal connection issues of Wired and Mesh APs. If your AP goes offline unexpectedly, follow the steps above for troubleshooting.