Troubleshoot WiFi connections | Troubleshooting Tools and Methods | Cisco Catalyst SD-WAN Troubleshooting Guide

Configure troubleshooting procedures to check and resolve connection problems between a WiFi client and a WiFi network provided by a WiFi router.

This task helps you identify and resolve connection problems between a WiFi client and a WiFi network that is provided by a WiFi router. The procedures described here are applicable to devices that support WiFi only.

Use this troubleshooting task when a WiFi client is unable to connect to a WiFi network when a router is providing the WiFi network. This task covers the most common issues that occur with WiFi connections between a WiFi client and a router.

Before you begin

Follow these steps to troubleshoot WiFi connections:

Procedure

Verify that the WiFi client can locate the service identifier (SSID) advertised by the router.

If the client cannot find the SSID, see the section about resolving SSID location issues.
Verify that the WiFi client can connect to the SSID advertised by the router.

If the client cannot connect to the SSID, see the section about resolving SSID connection failures.
Verify that the WiFi client has been assigned an IP address.

If the client cannot obtain an IP address, see the section about resolving missing IP address issues.
Verify that the WiFi client can access the Internet.

If the client cannot connect to the Internet, see section about resolving Internet connection failure.
Check WiFi connection performance if experiencing slow speeds or frequent disconnects.

If the WiFi client connection is slow or if you notice frequent disconnects, see section about resolving slow WiFi speed issues.
Resolve SSID location problems when the WiFi client cannot locate the SSID advertised by the router.
1. Ensure that the basic service set identifier (BSSID) address for the SSID is valid:
  1. From the Cisco SD-WAN Manager menu, choose Monitor > Devices.
    
    Cisco vManage Release 20.6.1 and earlier: From the Cisco SD-WAN Manager menu, choose Monitor > Network.
  2. Choose a device from the device list that appears.
  3. From the left pane, choose WiFi. The right pane displays information about WiFi configuration on the router.
  4. In the right pane, locate the SSID. Check that the BSSID for this SSID does not have a value of 00:00:00:00:00:00.
  5. If the BSSID is 00:00:00:00:00:00, the WLAN (VAP) interface for this SSID may be misconfigured. Ensure that the WLAN interface has been added to a bridge during the configuration process. To view the running configuration of the device, from the Cisco SD-WAN Manager menu, choose Configuration > Devices. For the desired device, click ...and choose Running Configuration.
    
    To view the running configuration of the device from the CLI, run the show running-config command. To add the WLAN interface to a bridge — from the Cisco SD-WAN Manager, choose Configuration > Templates.
    
    Click Feature Templates, and choose the Bridge feature template.
    
    Note
    
    In Cisco vManage Release 20.7.1 and earlier releases, Feature Templates is titled Feature.
2. Eliminate static channels. A static channel is one where you explicitly configure the radio channel rather than allowing the router to automatically select the best radio channel. A slow static channel may appear to be an unreachable SSID.
  1. View the current SSID channel setting for the router. To do this, from the Cisco SD-WAN Manager menu, choose Monitor > Devices and choose a device from the list of devices that appears. Then click Real Time, and in the Device Options drop-down list, choose WLAN Clients or WLAN Radios.
    
    From the CLI, run the show WLAN clients or show WLAN radios command.
  2. If the channel is set to a specific number, change the value to "auto". To do this, use the WiFi Radio feature template in Cisco SD-WAN Manager.
    
    From the CLI, run the WLAN channel auto command.
3. Ensure that the WiFi client is using the same radio band as the router, either 2.4 GHz (for IEEE 802.11b/g/n) or 5 GHz (for IEEE802.11a/n/ac):
  1. Check which radio band the WiFi client supports.
  2. Check the router's Select Radio setting. To do this, from the Cisco SD-WAN Manager menu, choose Monitor > Devices and choose a device from the device list that appears. Then click Real Time, and in the Device Options drop-down list, choose WLAN Radios.
    
    From the CLI, run the show WLAN radios command.
  3. If the router and WiFi client radio band settings do not match, either change the WiFi client's radio band or change the settings on the router so that they match. To do this, use the Wifi Radio feature template.
    
    From the CLI, run the WLAN command.
Resolve SSID connection failures when the WiFi client can locate the SSID advertised by the router but cannot connect to it.
1. If you configure passwords locally on the router, ensure that the WiFi client's password matches the SSID's password.
2. If you are using a RADIUS server, ensure that the RADIUS server is reachable and that the WiFi client's username and password match the RADIUS configuration:
  1. To verify that the RADIUS server is reachable from the router, ping the server. To do this in Cisco SD-WAN Manager, ping a device. From the CLI, run the ping command.
  2. Check for matching passwords on the RADIUS server and WiFi client.
3. Ensure that you do not exceed the maximum number of clients for this SSID:
  1. Verify the number of used clients and the maximum number of clients:
    - From the Cisco SD-WAN Manager menu, choose Monitor > Devices and choose a device from the device list that appears. From the left pane, select WiFi. In the right pane, locate the SSID. Check the No. of Clients field. If the used/maximum values are equal, no more clients can connect to this SSID.
    - From the CLI, run the show WLAN interfaces detail command.
  2. If needed, increase the maximum clients setting for your SSID. To do this use the WiFi SSID feature template in Cisco SD-WAN Manager.
    
    From the CLI, run the max-clients command.
4. Ensure that the WiFi client supports WPA2 management security:
  1. Check your Management Security setting. To do this, from the Cisco SD-WAN Manager menu, choose Monitor > Devices and choose a device from the device list that appears. Then click Real Time, and in the Device Options drop-down list, choose WLAN Interfaces.
    
    From the CLI, run the show WLAN interfaces command. If the management security value is set to "required," the WiFi client must support WPA2 security.
  2. If necessary, change the Management Security setting for your SSID to "optional" or "none." To do this in Cisco SD-WAN Manager, use the WiFi SSID feature template.
    
    From the CLI, run the mgmt-security command.
Resolve missing IP address issues when the WiFi client can connect to the SSID, but cannot obtain an IP address.
Ensure that a DHCP server is reachable and has an available IP address in its address pool:
1. If the router is acting as a DHCP helper (DHCP relay agent), ping the DHCP server to ensure that it is reachable from the router. From the CLI, run the ping command.
2. If you are using a remote DHCP server, check that the remote DHCP server has an available IP address in its address pool.
3. If the router is acting as the local DHCP server:
  1. View the number of addresses being used. From the Cisco SD-WAN Manager menu, Monitor > Devices and choose a device from the device list that appears. Next, click Real Time, and from the Device Options drop-down list, choose DHCP Servers.
    
    From the CLI, run the show DHCP server command.
  2. Compute the number of IP addresses in the pool based on the configured DHCP address pool size and the number of addresses excluded from the DHCP address pool. To view these values in Cisco SD-WAN Manager, from the Cisco SD-WAN Manager menu, choose Configuration > Devices. For the desired router, click ... and choose Running Configuration.
    
    To view them from the CLI, run the show running-config command.
  3. If necessary, increase the range of addresses in the router's DHCP address pool using the DHCP-Server feature template in Cisco SD-WAN Manager.
Resolve Internet connection failures when the WiFi client is connected to the SSID and has an IP address, but it cannot connect to the Internet.
Ensure that the WiFi client has received the correct default gateway and DNS settings from the DHCP server:
1. If the DHCP server is remote, check the settings on the server.
2. If the router is the DHCP server, ensure that the default gateway and DNS server settings are the same as those on the WiFi client. To view the settings in Cisco SD-WAN Manager, from the Cisco SD-WAN Manager menu, choose Monitor > Devices, and choose a device from the device list that is displayed. Click Real Time, and in the Device Options drop-down list, choose DHCP Interfaces.
  
  From the CLI, run the show DHCP interface command.
Resolve slow WiFi speed issues when the WiFi client can connect to the Internet, but the connection speed is slow.
Allow the router to choose the best WiFi channel:
1. View the current SSID channel setting for the router. To do this in Cisco SD-WAN Manager, from the Cisco SD-WAN Manager menu, choose Monitor > Devices, and choose a device from the device list that is displayed. Click Real Time, and in the Device Options drop-down list, choose WLAN Clients.
  
  From the CLI, run the show WLAN clients or show WLAN radios command.
2. If the channel is set to a specific number, change the value to "auto". To do this in Cisco SD-WAN Manager, use the WiFi Radio feature template.
  
  From the CLI, run the WLAN channel auto command.

WiFi connection problems between the client and router are identified and resolved. The client can successfully locate the SSID, connect to it, obtain an IP address, and access the Internet with optimal performance.