How to configure a TP-LINK router to become an Access Point

How to configure a TP-LINK wireless WiFi router to turn it into a Wireless WiFi Access Point

What: How to configure an inexpensive TL-WR340GD or TL-WR-642G or TL-WR1043ND (the D stands for Detachable antenna) wireless router (manufactured by TP-LINK) to become a wireless WiFi Access Point. Other models of TP-LINK wireless routers may be similarly configured.
You can do similiar conversions with Linksys WRT54G, however, TP-LINK wireless router costs less than Linksys; so far I found no quality or performance issues with TP-LINK; newer Linksys/Cisco wireless routers use "internal antennae" therefore you cannot increase wireless WiFi coverage by replacing the detachable antenna with external high-gain antenna.

Why: Typically if you have a wireless router in the home or office (just behind a cabled modem or DSL modem, see this diagram), the wireless router should be configured as a router (factory default configuration). However, you may want to add a secondary wireless device to expand your WiFi wireless coverage (see this diagram), it is much better to configure the secondary wireless device as an "Access Point" instead of a "router behind a router". Reasons: all your internal computers and peripherials are now on the same IP network so they can share resources and communicate with each other as if they were connected by traditional CAT-5 wire and switches.

Why not use the "bridge mode" that is natively available in TL-WR340G or WR-642G? Because the bridge mode available in TP-LINK only supports WEP encryption. The master key in WEP can be recovered very easily using popular BackTrack software. In this tutorial, you can configure your wireless network to use safer WPA2/PSK encryption scheme. For WPA2, you still need a strong (non-dictionary word) password consists of letters, numbers and special characters.

Pre-requisites:
A primary wireless (or non-wireless) router, see this diagram; and a CAT-5 cable run between the primary and secondary devices, see this diagram.
Find your local area network IP address range - on a networked PCs, pop a "cmd" screen and
For Windows XP, type (case sensitive) ipconfig | find "Address" to get an idea of what it might be.
For Windows Vista / Windows 7, type (case sensitive) ipconfig | find "IPv4" to get an idea of what it might be.

How:

Make sure the TP-Link TL-WR340G or TL-WR-642G is reset to factory default state. To reset, push and hold a pin in the reset hole, then power up, continue to hold the pin pushed in for 10 seconds. Remove the pin.

Since you are configuring the WR-340G or WR-642G to be an Access Point, the WAN port (blue port) will not be used, plug it with tape to avoid confusion.

Connect a CAT-5 cable from a laptop to one of the LAN ports (yellow port) on WR-340G or WR-642G. See this diagram. Reboot the laptop if necessary.

On the laptop, invoke a web browser: http://192.168.1.1/ user name is admin, password is admin

Go to DHCP Settings, select "Disable DHCP Server". See this diagram. Click Save.

Go to Network Settings, select "LAN", change the "IP Address" to an un-occupied static IP address in your local area network (e.g. 10.5.1.7). Your LAN IP address range is likely to be different than 10.5.1.xx, it is determined or influenced by your primary router's DHCP settings. See this diagram. Click Save. Once you click Save, the WR-340G will reboot itself and your laptop will loose connection to the WR-340G

Reconfigure your system as follows:

Connect a live CAT-5 cable from your primary router (or LAN switch or hub) to the LAN port (yellow port) of the secondary Access Point (i.e., the WR-340G or WR-642G). See this diagram.

Reconnect the laptop to your normal LAN, or reconnect the laptop to the primary wireless router Access Point. See this diagram. Reboot the laptop if necessary.

Invoke a web browser: e.g. http://10.5.1.7/ (your IP address is likely different than mine)
user name is admin, password is admin

You now regain connection to your WR-340G or WR-642G, do the remaining steps, for example,
-Set the wireless SSID to be something more meaningful to you, e.g. my-workshop
-Select an appropriate wireless channel (avoid using the same channel as your primary wireless router; avoid using your neighbours wireless channels) (most WiFi devices for North American market are (factory) default to use Channel 6).
-Enable wireless security (in Wireless Settings, choose WPA-PSK//WPA2-PSK in the Security Type drop down list)
(if you have a radius server, choose WPA/WPA2, most home/small businesses do not use radius servers)
-Change the admin password to a more secure password.

You now have added a fully functional Wireless Access Point to your local area network !

Other Applications:
If you live in a castle or large mansion or large property that needs extensive WiFi coverage, you can go crazy by daisy chaining several inexpensive TP-LINK Wireless Access Points like this diagram.
Free WiFi can be deployed in cheap hotels to compete with business-grade hotels with "Free Wireless Internet Access". Disclaimer.

Performance Tweaks:
You can increase WiFi signal strength (increase the number of "bars" on the signal meter) by replacing TP-LINK's original 5 dBi omni antenna with a 7 dBi or 9 dBi omni antenna (with RP-SMA connector) or a wall-mounted Patch Antenna, or mast-mounted Yagi, or a cheap home made near cookware parabolic or home made dog dish parabolic or an ultimate professional 24 dBi long range grid parabolic antenna. For an auditorium size or concert hall size room, a high gain corner-antenna (e.g. Hawking Technology HAI15SC should do a good job of providing WiFi coverage). Below are some sample websites where you can find high gain 2.4 GHz WiFi frequency band antennae:

www.data-alliance.net www.l-com.com www.superpass.com (Waterloo, ON)

Note: for omni antenna (aka rubber duck antenna), the increase in signal is in the "horizontal direction", another word, on the same floor. Basically these antenna refocus the energy and concentrate them in the horizontal direction (assuming the tip of the rubber duck is oriented upwards). High gain omni will reduce radiation energy to the upper and lower floors, but will increase radiation energy on the same floor. Antennae do not create energy, they just redirect and refocus energy.

Final step:

In the above configuration, the WAN is constantly trying to obtain an IP address adding unnecessary load on the CPU. Configure the WAN to use "static IP" to reduce this annoyance:
Network settings, WAN, use "Static IP", IP address (see RFC1918. Choose an IP that you'll never use, e.g. 10.99.99.99, use subnet mask 255.255.255.0), click Save. See this diagram.

Disclaimer