III. Wireless LAN

Troubleshooting Wireless LAN (Wi-Fi) if throughput is less than expected

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If the Wi-Fi signal is strong, but the speed is slow or you get disconnected quite often, you may try the following to improve the Wi-Fi performance of your Vigor Router or VigorAP, including:

1. Change the wireless channel

The Wi-Fi will have a lot of interference and start dropping packets if it is using a channel too crowded. You may use AP Discovery or Interference Monitor function to check for nearby APs and the channels they're using, then use a channel that is less used by the others.

Wireless LAN >> AP Discovery >> Statistics shows the recommended channels to use after a scan

3. site survey statistics

Selected VigorAPs also provide Interference Monitor under the Diagnostic menu. It recommends the best channel based on the traffic on each channel (Channel Utilization), as well as the electromagnetic field detected on each channel (Channel Energy, not necessarily generated by APs, can also by the electronic devices).

interference Monitor All Channel

 Once you have analysed the best channels for wireless usage, you can select the best channel in Wireless LAN >> General Setup.

2. Adjust the Channel bandwidth

By default, the wireless channel bandwidth is 20/40MHz, which means the router or AP may use two 20MHz channels at the same time to double the throughput. Stay on the default settings if there's not much interference on your network. However, if there is a lot of interference, lower the bandwidth to 20MHz so it would use only one least-crowded channel. Channel Bandwidth option is on Wireless LAN >> Advanced Setting page.

02 channel width

3. Deploy 5GHz Wi-Fi and Enable Band Steering

5GHz radio is usually much less crowded than the 2.4 GHz band so that it can offer better Wi-Fi performance. If you are using a dual-band AP, try to enable Band Steering to redirect the 5GHz-capable clients to the 5GHz SSID. On Vigor Router and Vigor AP, this can be achieved by setting up a pair of SSIDs with the same name and password on both 2.4GHz and 5GHz WLAN, then check Enable Band Steering at Wireless LAN (2.4GHz) >> Band Steering page.

3 band steering

4. Lower the RTS Threshold

RTS (Request to Send)/CTS (Clear to Send) is a mechanism to reduce collision among stations, but using RTS/CTS will add more overhead; therefore, by default, the AP only use RTS/CTS when transmitting a packet larger than 2347 bytes. In a network having many stations far apart from each other, you may lower RTS threshold to several hundred bytes to implement the RTS/CTS more often. RTS threshold option is on Wireless LAN >> Advanced Setting page.

03 rts threshold

5. Enable Airtime Fairness

APs are using packet fairness by default; therefore, a slow device might slow down the whole wireless network because the AP would need to spend more time on them to transmit the equal amount of packets. In this case, Airtime Fairness can be the solution. If there are plenty of wireless clients on the network and some of them might have weak signal strength, you can enable Airtime Fairness in Wireless LAN >> Airtime Fairness to make sure the AP spend the equal of time on each client and prevent most of the clients from being delayed by those slow ones.

Enable AirTime Fairness

6. Use WPA2/PSK for authentication

If you have a Wi-Fi device that will not connect to the router's Wi-Fi or you are experiencing poor speeds, check that the SSID's security mode is set to WPA2/PSK. This is currently the most secure Wi-Fi authentication form supported by all latest Wi-Fi devices, we recommend this mode for Wi-Fi authentication. To set this up, go to [Wireless LAN] > [Security], and for each of the configured SSIDs select WPA2/PSK as the encryption mode. Using WPA/PSK or WEP will significantly decrease wireless speeds for compatibility purposes.

7. Disable EAPOL Key retry

EAPOL (EAP over LAN) is the method used by WPA2 to exchange identities in both WPA2/PSK and WPA2/802.1x (Enterprise) modes and to install the keys to establish an encrypted connection. Within WPA2, if a response is not received by a station (client) it can request a resend. This may be important in a 'noisy' environment - that is one with a lot of wireless traffic and interference where responses may be lost. This can also however cause issues such as reducing speeds and disconnecting unresponsive clients.

To view and change this setting, go to Wireless LAN >> Security, the EAPOL Key Retry setting is set to Enabled by default. Set EAPOL Key Retry to Disable to stop EAPOL retries and click OK to apply the setting.


8. Ensure your router or AP is running the latest firmware version

We always recommend the use of the latest firmware for your product to ensure that you have the latest features as well as vital security improvements. Sometimes, these improvements increase performance. To check for the latest firmware version for your device, visit our Downloads page.

9. Adjust wireless antenna positioning

Make sure the antennas are connected firmly to the router or AP, then tweak the direction of the antenna to make a better signal. The aerials don't necessarily need to be in the traditional 'straight up' orientation. Experimentation is always recommended.

10. Keep away from obstruction and interference

Walls, ceiling, doors, and cabinet will all decrease the radio signal. Reduce the obstacles between the router/AP and the clients as much as possible. And note that a microwave oven, cordless phone, or Bluetooth devices are also operating on the 2.4 GHz radio and thus can interfere with the wireless.