[Troubleshooting]PC cannot obtain the IP address

We have talked about how to handle the AP online failure. Today, we will talk about how to handle the failure to obtain an IP address or the failure to connect to the wireless network when a PC or mobile phone is connected to the wireless network. The terminal fails to connect to the wireless network or fails to obtain an IP address because the terminal keeps turning around when connecting to the wireless network, and a message is displayed indicating that the connection fails or an IP address of 169.254.x.x is obtained. If the preceding fault occurs, it indicates that the terminal fails to connect to the wireless network.

Handling Approach

Check whether the terminal is disconnected from the wireless network or cannot be connected to the wireless network.
Run the display station online-fail-record sta-mac xxxx-xxxx-xxxx command on the AC to check the cause of the failure.
Check AC configurations, such as VLAN and VAP profile configurations.
Check whether the MAC address of the terminal is added to the AC blocklist.
Check the AP channel usage and wireless environment.
Check the number of terminals connected to the AP.
Check whether the terminal model is too old.
Check the Logbuffer and Trapbuffer logs to determine whether the cause of terminal disconnection exists.
Collect diag logs and trace information.

Handling Procedure

Check whether the terminal is disconnected or cannot be connected to the wireless network. Check whether the terminal is disconnected during the connection. If the terminal is disconnected during the connection, check the logs. If the STA cannot connect to the wireless network on a new WLAN, check the AC configuration. You can use different troubleshooting methods based on the fault symptom.
Run the display station online-fail-record sta-mac xxxx-xxxx-xxxx command on the AC to check the cause of the STA login failure. You can run this command to check the cause of the STA login failure. For example, if the password is incorrect, the STA is added to the blocklist, or the STA is beyond the limit of the AP. You can view this command directly. It is very simple to use this command in the troubleshooting method of terminal online failure. For the error information displayed in this command, you can view the specific handling method in the AC product documentation or the AC maintenance guide.
Check AC configurations, such as VLAN and VAP profile configurations. If the management service VLAN is incorrectly configured or the service VLAN is the same as the management VLAN, STAs may fail to obtain IP addresses. Check whether the VAP profile is incorrectly configured. For example, the SSID profile, security profile, or RF port is incorrectly bound. If the VAP profile is incorrectly bound, the STA fails to connect to the wireless network.
Check whether the MAC address of the terminal is added to the AC blacklist: This step is to check whether the MAC address of the terminal is added to the AC blocklist. If yes, delete it first. Wireless connection test is being performed. You can run the display sta-blacklist-profile name black and display wlan ids dynamic-blocklist all commands to check the static and dynamic blocklists of the AC. If no MAC address of the STA exists, If the MAC address exists, delete the MAC address of the terminal.
Check the AP channel usage and wireless environment. Check the AP channel usage to check whether the AP rejects the connection because the AP channel usage is too high. If the AP channel usage is too high, try to connect to other APs or wait until the channel usage decreases. Check the radio environment. You can use software to scan whether the surrounding radio signal sources are too large or whether the surrounding interference is too large. If there are a large number of scanned signal sources, you are advised to enable RF optimization to adjust radio channels. The AC has this function. You can set the optimization mode to manual or automatic. The following commands are manual optimization commands.
Check the number of terminals connected to the AP. The number of terminals connected to the AP is limited. If a large number of terminals are connected to an AP, you are advised to connect to other APs. If an AP is connected to a large number of terminals, the wireless rate is slow, the Internet connection is interrupted, and the wireless connection fails. You can run the display station ap-id x command to check the number of terminals connected to the AP.
Check whether the terminal model is too old. There are not many reasons why the terminal cannot connect to the wireless network. However, we also need to check this step. If the terminal model is too old to connect to the wireless network, the common reason is that the terminal does not support the AC key algorithm, 5 GHz radio, or authentication mode. If a terminal of an old model cannot connect to the wireless network, this may be the reason.
Check the Logbuffer and Trapbuffer logs to determine whether the cause of terminal disconnection exists. If the basic configuration information is checked and the cause of terminal connection failure cannot be determined, check the log information of the device to determine whether the terminal connection failure exists.
Collect diag logs and trace information. If all the preceding steps are performed, the cause of the terminal connection failure or the cause of the terminal disconnection cannot be determined. Then, collect the diag log information and trace results of the device and contact the TAC center for assistance.