III. Wireless LAN

DrayTek VigorAP - Troubleshooting

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DrayTek VigorAP – Troubleshooting

Wireless networks are an integral part of today's network infrastructure, many network deployments now contain an element of wireless connectivity. With the increasing trend towards much more mobile devices and seamless connectivity the emphasis on your wireless network has increased. Now, more than ever, the smooth running of your wireless network is essential to a good user experience and decent network performance. However, deploying a healthy wireless network is infulenced by a number of factors, many environmental, and the following sections of this guide provide some product specific knowledge as well as general tips and tricks which can help you get the most out of your wireless network.

Section 1 – Accessing the VigorAP

By default the AP-900 is configured as a DHCP client. This means that it should pick up a dynamic IP address from a local server.

To find out which IP address you need to use to access the device you should check the local DHCP server and match the MAC address of the AP-900 to the IP address listings in its ARP cache table or DHCP table.

If you have a DrayTek router handling DHCP then you can check this from the routers Diagnostics menu:

If you are using a local Windows server or alternative device then similar details can be found by accessing that device. If you encounter issues with this please contact the appropriate support department.

NOTE: If the AP-900 is unable to contact a DHCP server then it will revert back to as its default IP address. This is useful information if you are connecting a PC directly into the AP-900 without connecting it to the local network.

Simply give your PC an IP address within the subnet and you should be able to access the AP-900 directly.

Section 2 – I know the IP address but can’t access the device.

This issue will normally pop up when using VLAN tags on the network. You might know the IP address of the device but if the proper VLAN configuration isn’t in place on the local network then you might not be able to access the device.

For example:


In this example we have a different subnet allocated to the AP-900 and we also have a management VLAN ID for LAN access to the device.

With this configuration in place you would need to be a part of that subnet but also be a part of the correct VLAN on the network. This requires the correct configuration to be in place on all network infrastructure such as the router and any switches you are using.

If, for example, you were to remove this AP-900 from the network and plug a PC directly in to it you would not be able to access the AP as the PC is unlikely to be able to provide the correct VLAN tags for communication.

In situations like this, especially if you happen to lock yourself out of the device and are unsure what to do, the best option is often just to factory reset the AP-900. It will restore to its original settings and you should be able to access the device for further configuration.

Section 3 – I've configured the RADIUS server but keep on getting asked for a Pre-Shared Key.

In some circumstances users will have configured their wireless network to use RADIUS authentication. Some devices will connect without issues and some will ask for a pre-shared key instead of a username/password.

This issue occurs in situations where the AP-900 has been successfully configured to use RADIUS in the 2.4ghz range. However, the AP-900 is a Dual Band device and also gives out an SSID within the 5ghz range. This issue will occur when the SSID for both the 2.4ghz and 5ghz is the same but the RADIUS has NOT been configured for the 5ghz profile. Essentially the wireless clients will connect to the network transparently and some 5ghz capable devices will automatically select the 5ghz range. As this SSID has not been configured for RADIUS it will ask for a Pre-Shared Key.

Fortunately the solution to this problem is very straight forward. Simply make sure that the 5ghz range has been configured with the same RADIUS settings as the 2.4ghz profile. 

Section 4 – I get poor coverage/signal strength drops out/slow speeds.

WLAN's offer a very convenient and cost effective way of providing mobilty to uses of the network. Previously providing network access at a specific point would require cabling for each client and in many scenarios this was not a straight-forward task. The advent of IEEE 802.11 wireless has helped greatly however there are still local/environmental issues that may need to be overcome. The 2.4GHz and 5Ghz frequency bands are not exclusively reserved for 802.11 devices (dect phones for example also use 2.4GHz and microwave ovens can leak this frequency) and also neighbours may also be competing over the same bands.

Below are some general tips that may help improve coverage but also check our generic WLAN troubleshooting articles as the advice also applies to the AP-900.

Things to consider:

-        Placement of AP’s. Thick walls, insulation, metallic surfaces, etc can all cause significant problems for wireless signals. Try and place the AP in an open area with good line of sight.

-         Channel congestion. When using AP mode try and space out the channels which are being used. Channels 1, 6 and 11 do not have any overlap. Intelligent use of channel bandwidth based on AP location can stop your own AP’s from interfering with each other.

-         Wireless congestion. If you are in an area with a very large number of SSID’s and other wireless networks then you might want to consider jumping over to the 5ghz range, or using both. It is generally less congested than the 2.4ghz range and could give better performance. Devices that are only able to use 2.4GHz will also benefit if the 5GHz capable devices are using 5GHz.

-         Electro-magnetic interference. Try and avoid placing AP’s near high voltage machinery and any device which emits strong electromagnetic radiation while in use. DECT phones and microwaves are common devices which cause wireless interference.

-         Legacy devices. Older devices which do not support 802.11n will slow down the entire network. The wireless network must run at the same speed as the slowest device.

-         Aerial orientation/selection. There is a section of the website which goes into aerial gain and wireless propagation in detail. Check it out, it will give valuable insight into the type of aerial to use to match your needs.

Section 5 – Windows 8.1 WLAN profiles.

This is completely unrelated to DrayTek products but is something that we have run into when setting up the AP-900.

The wireless profiles on a Windows 8.1 machine can only be actively modified under certain conditions. Sometimes the only way to amend the wireless details for a particular connection is to delete it entirely and then start again.

Microsoft have made this a very difficult process in 8.1, you will need to use the command prompt to perform this action.

Firstly, access the windows command prompt by hitting the windows button and then enter ‘cmd’ (minus quotation makrs). Then hit enter. You should then see the black windows command prompt show up on your desktop:

You should then enter the command as shown above:

Netsh wlan delete profile name=”profile 1”

You should replace the ‘profile 1’ with the name of the SSID you wish to remove. Once this is complete you can then add a new wireless profile using the Network and sharing centre. This will then allow you to modify the various RADIUS and encryption settings for that profile.

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