Troubleshooting guide of common wireless issues

Contents

Objective

Requirements

Introduction

Troubleshooting

Troubleshooting with Controller Logs

Troubleshooting: Clients Cannot Detect AP Wi-Fi

Troubleshooting: Clients Unable to Connect to AP Wi-Fi

Troubleshooting: Clients Unable to Obtain an IP Address

Troubleshooting: Clients Unable to Access Local LAN

Troubleshooting: Clients Unable to Access the Internet

Troubleshooting: Poor Throughput

Troubleshooting: Abnormal Client Behaviors

Conclusion

Objective

This article introduces how to troubleshoot some common wireless issues.

Requirements

• Omada AP
• Omada Controller (Software Controller/Hardware Controller/CBC, v5.9 and above)

Introduction

When using the network, wireless clients sometimes may encounter various wireless issues such as clients cannot detect AP’s Wi-Fi, clients unable to connect to AP’s Wi-Fi, clients not getting an IP address, clients unable to access local LAN, clients cannot access the internet, poor throughput, etc. This article will show you how to troubleshoot common wireless issues.

Troubleshooting

Troubleshooting with Controller Logs

The Controller logs can record some abnormal client behaviors, such as inability to associate, roaming or authenticate. It is recommended that you enable all types of client events in the controller log, so that if the client encounters a wireless problem, it can check the controller log to find the cause of the anomaly and quickly narrow down the scope of the troubleshooting.

Troubleshooting: Clients Cannot Detect AP Wi-Fi

Step 1. Check whether the WLAN Group used by the AP contains the target SSID.

Step 2. Check whether SSID Broadcast is enabled on the target SSID.

Step 3. Check whether WLAN Schedule is enabled on the target SSID.

Step 4. Check whether SSID Override is enabled on the target SSID.

Step 5. Check whether the Radio is enabled on the target SSID.

Step 6. Check whether the AP's actual working channel is the DFS Channel.

Step 7. Please confirm whether the client supports the working channel of the current AP.

Troubleshooting: Clients Unable to Connect to AP’s Wi-Fi

Step 1. If the Wi-Fi password has changed, clients that record the previous password will fail to connect to the Wi-Fi. In this case, please forget the network on the clients and re-enter the password to associate Wi-Fi.

Step 2. Check the Security Key and enter the correct password to associate Wi-Fi.

Step 3. Check whether the Network Name contains non-ASCII characters, which may cause clients to be unable to recognize it. If it does, please delete the related characters and try again.

Step 4. Check whether the clients support the configured WPA Mode. If WPA3 encryption is configured, some IoT devices or 802.11n devices may be unable to associate normally. In this case, you can change WPA Mode such as WPA/WPA2-PSK and reconnect the clients.

Step 5. Check whether the SSID is configured with the PMF function. When the PMF function is set to Mandatory, clients that do not support PMF may be unable to connect to the network. In this case, you should disable the PMF function and try again.

Step 6. Check the client’s signal strength. If the Wi-Fi signal strength at a client is weak, the client association will fail. In this case, you can move the client closer to the AP and reassociate.

Step 7. Confirm whether a third-party authentication server is required during the association process.

• Check whether the Security method of the SSID is WPA-Enterprise or PPSK with Radius.
• Check whether the MAC-Based Authentication function is enabled.
• If a Radius authentication server is required, check whether the Radius Profile is configured correctly.
• If customer uses PPSK with Radius encryption or enable MAC-Based Authentication, make sure that the MAC-Address Format is consistent with the format used in the Radius server.

Step 8. Check whether MAC-related functions are configured to prohibit access of specific clients.

• Check whether MAC Filter is enabled. If MAC Filter is enabled for the SSID with the deny list, clients in the list will be unable to associate with the SSID.
• Check the Blocked list on the Insight page. You can go to Insight > Known clients > Blocked and check. Clients in the blocked list will be unable to access the network.
• Check whether Lock to AP is enabled. If Lock to AP is enabled, the client can only associate with a specific AP. You can go to Insight > Known Clients, select the corresponding time and client to check whether the client is locked to a specific AP.
• Check the WIPS Dynamic Block List (supported only in Omada Pro Controller). If the above function is configured, you need to disable it and try to associate again.

Step 9. Check whether Load Balance is enabled.

• Check whether Maximum Associated Clients is enabled. If it is enabled, check whether the number of currently connected clients has reached the threshold.
• Check whether RSSI Threshold is enabled. If RSSI Threshold is enabled, clients with signal strength below the set threshold cannot access the network. During troubleshooting, you can try to disable this function or move closer to the AP to reconnect.

Step 10. Check if 802.11Rate Control is enabled. For example, if Rate Control is set to 24M on 2.4G, devices with a negotiated rate lower than this rate, such as 802.11b-only devices, will be unable be connect. In this case, you can turn off this function and try to reconnect the clients.

Step 11. Check whether Deauthenticate is enabled (supported only in the Omada Pro Controller).

Troubleshooting: Clients Unable to Obtain an IP Address

Step 1. Check whether the DHCP server is reachable. You can use the Network Check function provided by the Controller to test connectivity.

Step 2. Check whether the DHCP address pool has any available addresses. If the DHCP address pool has been fully allocated, expand the address pool.

Step 3. Check whether the VLAN configuration in the network is correct.

• Check whether SSID VLAN is enabled. If SSID VLAN is enabled, check whether the corresponding ports of the switch and gateway in the network are configured with the corresponding VLAN.
• If the SSID’s Security is PPSK without Radius, check whether the PPSK profile is configured with VLAN attributes, and check whether the corresponding ports of the switch and gateway at the front end of the network are configured with the corresponding VLAN.
• If a Radius authentication server is required, check whether VLAN is enabled in the Radius Profile and whether the VLAN authorization attribute configuration in the Radius server is correct. For example, the Tunnel-Type value is fixed to 13 (or VLAN); the Tunnel-Medium-Type value is fixed to 6; and the Tunnel-Private-Group-ID value is the divided VLAN number. Check whether it is the expected VLAN value.
• For AP models with downlink ports, also check whether the Port VLAN is enabled, and whether the corresponding ports of the switches and gateways at the front end of the network are configured with the corresponding VLAN.

Troubleshooting: Clients Unable to Access Local LAN

Step 1. Check whether the SSID that the client associates has enabled Guest Network. It is normal that the guest network cannot access the local LAN.

Step 2. Check whether ACL is enabled.

Step 3. Check whether the client has set up firewall rules. Please disable the firewall and try again.

Troubleshooting: Clients Unable to Access the Internet

Step 1. Check whether the network parameters obtained by the client are correct.

• If there is an illegal DHCP server in the network that assigns a wrong IP address or gateway to the client, the client will be unable to access the Internet. Therefore, it is necessary to check whether the parameters such as the IP address, subnet mask, and gateway IP address obtained by the client are correct. If they are incorrect, find the illegal DHCP server and remove it.
• If the client uses the static IP address, ensure that it is configured with the gateway IP address and the DNS server IP address.

Step 2. Check whether there is an IP conflict on the client. If IP conflict occurs, the client's IP address cannot be used normally. You can check for IP conflict in the following two ways:

• Check the client IP addresses in the Clients list of the Controller.
• Check whether there are duplicate IP addresses in the DHCP Client List on the DHCP server.

Step 3. Check whether the connectivity between the client and the gateway is normal.

Step 4. Check whether the connectivity between the client and the DNS server is normal.

• Check whether the client can ping the DNS server.
• Check whether the DNS resolution is normal. For example, in Windows system, enter the nslookup command in the cmd window, such as nslookup www.google.com , to see if there is a response.
• Change the DNS server address to the IP address of a public DNS server, for example: 8.8.8.8, and try again.

Step 5. Check whether the wired network can access the Internet normally. Connect a wired client directly through the gateway or switch at the front end of the network to check whether the wired client can access the Internet normally. If not, check the wired network.

Step 6. Check whether there is severe interference in the wireless environment, which prevents the client from accessing the Internet. When the channel utilization of the associated frequency band is greater than 70%, the user's Internet experience may be affected. Check the channel utilization. If the channel utilization is too high, it is recommended to switch to a channel with lower channel utilization.

Step 7. Check whether there are illegal multicast or broadcast sources occupying wireless resources. Check the multicast and broadcast message statistics on the Omada Controller (supported by Omada Controller 5.14 and above). If there are too many multicast or broadcast messages in a short period of time, it is recommended to enable Multicast/Broadcast Rate Limit (supported by Omada Controller 5.14.30 and above) or Multicast Filtering (supported by Omada Controller 5.9 and above).

Step 8. Check whether the communication rules are configured to restrict the client's Internet access. It is recommended to turn off the special configuration and then try to access the Internet.

• Check whether EAP ACL is enabled.
• Check whether URL Filtering is enabled.
• Check whether Portal authentication is enabled.

Step 9. Check whether the client has set up firewall rules. Please disable the firewall and try again.

Troubleshooting: Poor Throughput

Step 1. Check the client signal strength in the Clients list. Generally speaking, the client signal strength is required to be greater than -65 dBm. If the client signal strength is too weak, you can:

• Adjust the AP's transmit power to increase coverage.
• Increase the number of AP to eliminate coverage blind spots and weak signal areas.
• Move the client closer to the AP and test again.

Step 2. Check the AP channel utilization. If the channel utilization is higher than 70%, it may affect the user's network experience. In this case, you can:

• Manually set a clean channel for testing.
• If multiple APs are deployed, it is recommended to enable WLAN Optimization to automatically deploy power and channels to reduce interference between APs.

Step 3. Check the multicast and broadcast traffic in the network. If there are too many multicast and broadcast messages, a large amount of air interface resources will be occupied, affecting the normal network experience of the client. In this case, it is recommended to use the following methods to control multicast and broadcast traffic:

• Enable Multicast/Broadcast Rate Limit (supported by Omada Controller 5.14.30 and above).
• Enable ARP-to-Unicast Conversion (enabled by default in Omada Controller 5.14.30 and above) and Multicast-to-Unicast Conversion (enabled by default in Omada Controller 5.9 and above).
• If there is no multicast application in the network, you can enable Multicast Filtering.

Step 4. Check whether there are other clients in the network that are performing large-volume operations, such as downloading large files. You can view the traffic usage information of each client in the Clients list. In this case, you can set Rate Limit.

• Enable SSID Rate Limit. SSID Rate Limit sets an overall speed limit for all clients associated with the SSID.
• Enable Client Rate Limit. Client Rate Limit limits the speed of a single client.

Step 5. Check whether there are many clients with weak signals and low rates in the network. You can view RSSI information in the Client list. In this case, you can enable RSSI Threshold to eliminate clients with weak signals.

Step 6. Check whether the AP which the client is currently connected is overloaded. If so, enable Maximum Associated Clients to control the number of clients that can access the AP.

Step 7. Check whether Band Steering is enabled (enabled by default in Omada Controller 5.14 and above). The interference in the 2.4G band in a wireless environment is generally stronger than that in the 5G/6G band. Therefore, it is recommended to enable Band Steering and set it to Prefer 5GHz/6GHz to guide clients that support 5GHz/6GHz to associate with the 5GHz/6GHz band first.

Step 8. Check if there is any other Wi-Fi interference in the network environment. Please conduct a comparative test after eliminating the interference source.

Troubleshooting: Abnormal Client Behaviors

Use different clients to test to check whether the wireless issues only occurs on a specific client. If yes, it is recommended to restart the client and try again.

Conclusion

This article provides a detailed troubleshooting analysis of some common wireless issues. If you encounter related wireless issues, you can follow the troubleshooting process in this article to troubleshoot.

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