If you want to improve your WiFi connection, you have to perform some actions that influence on several factors important to WiFi Performance, ranging from changing the transmit power to change the transmission channel. In this article we will see how to configure your router taking as an example a D-Link DIR-505 model. However, the parameters to be modified are standard for any model or make of commercial router.

First we see some basic concepts to understand the nature of the optimal performance of a commercially available WiFi router for home.

Transmit Power

This is the power which the router uses to transmit any signal, normally any router operates at 100% power. However, in some cases, we have to isolate specific frequencies to a some area. We can do it by reducing the power of the radio, we can prevent interferences transmissions affecting beyond  corporate/home office or designated wireless area.

WMM Enable

Wireless Multimedia Extensions (WME), also known as Wi-Fi Multimedia (WMM), provides basic Quality of service (QoS) features to IEEE 802.11 networks. WMM prioritizes traffic according to four Access Categories (AC) - voice, video, best effort, and background. Enabling WMM can help control latency and jitter when transmitting multimedia content over a wireless connection.

Short GI

In telecommunications, guard intervals (GI) are used to ensure the different transmissions to not interfere with each other. The mode and the guard interval is an engineering decision depending on the topography  and implementation characteristics.

IGMP Snooping

IGMP snooping is to listen to the traffic generated by the network protocol IGMP (Internet Group Management Protocol). This feature allows network switches to 'hear' the conversation that occurs between routers and hosts. This allows too the switch to be capable of maintaining a map of the links that need multicast transmissions and thus handle the traffic so that only the ports need specific traffic to receive it. Some routers uses the IGMP protocol to support efficient multicasting -- transmission of identical content, such as multimedia, from a source to a number of recipients. This option must be enabled if any applications on the LAN participate in a multicast group.

WLAN Partition

Enabling WLAN Partition prevents associated wireless clients from communicating directly with each other.

Transmit Channel

The 802.11 workgroup currently works in 2.4 GHz bands and other frequencies.  This band is divided into a multitude of channels. Countries apply their own regulations to the allowable channels,  maximum power and range levels within these frequency. In some countries,  operators may use some of the channels at much higher power for long distance wireless access.
HT20/40 Coexistence
This refers to wideband of each channel. Enabling this option may prevent an undesirable interference of your device over your neighbors. Disabling can improve your connection speed.

Configuring your Router

As example, we are going to work on a D-LINK DIR-505 model, but almost all of these characteristics are available on any model or brand.
Here we can observe some of the previous mentioned characteristics, in the 'advanced' tab, then 'advanced wireless' at left bar. The decision of enabling/disabling these configuration options depends on what you really need, attending the above concepts and definitions.

Channel

You can change your transmit channel, but prior to do this you must be sure of what channel is less used in your neighborhood. For this you can use some software tools just like 'WIFI Radar' for Linux or WIFI Optimizer for Android.

WIFI Radar

This software lists your neighborhood WiFi Channel usage

WIFI Optimizer

This software plot all the channels and their usage

Based on this you can decide what channel to use, obviously, the less used channel is the recommendation.

In some cases, if you are experienced problems and  need to call ISP Support they can claim that everything is fine on their site and you will be stuck with your internal network problems. So, you as user may need be able to debug and fix certain network problems and it could be of a great help to you.

Common Network layout (topology)

First make sure that you know your network layout. Most probably it will be one of the following:

a) Modem -> Router (Cable+Wi-Fi) -> PC
b) Modem (Cable+Wi-Fi) -> PC
c) Modem ->  Switch -> Router (Cable+Wi-Fi) -> AP (Repeater)  -> PC

If router is not present in your network, it means that modem is working  as a router and it is important to know how to connect to modem administrative interface.
In Windows, to get some details about your network type ipconfig/all from cmd.exe launched under Administrative privileges. This command will show you lots of useful information about your network including address of the default gateway (for example we will use 192.168.1.254).
In case of layout a) this address will be of your router. And in case of b) and c) it will be the modem address. 
In Linux, the equivalent command is ifconfig -a.

Check connection to default gateway

In Windows and Linux you can type the following command either in cmd.exe or Terminal emulator (Linux).

ping 192.168.1.254

Instead of 192.168.1.254 you should use default gateway address you got in previous step (ipconfig /all or ifconfig -a)
The replies (no errors) means that your computer can see modem or router without any problems.
When you use ping command you can see some parameters like the length of the packet, icmp_seq, time to life and time of response. There could have some three options:

  •     All the package received (0% packages lost)  what means that the connection is fine.
  •     Some packages received (0%<packages lost<100%) what it means there must be some interferences or other problems.
  •     All packages lost (100% packages lost) means that there is not connection between PC and router.

The time of response is important too what means the delay of receiving packages and is subject to interference, obstacles, among others..

Most commercial routers comes with an IP address,  username and password by default. Talking about the user and password, it is assumed that the user must change this setting to customize the security of their device. However, unfortunately many users never change the default password of the router which represents a security risk for home or office network.
In many cases, the user may forget the password for their router, then it may work the default password that was setup in factory. In case you can not remember the password then refer to the user manual which has details about how. As a last resort you can manually reset the router considering that this action will erase your custom settings, however, this action can also restore the default password which is the main theme of this mini tutorial.
Each manufacturer uses a different IP address, username and password for their devices. Here's a short list of most common commercial devices in more detailed way. It is not accurate or exhaustive, because it does not include all models of routers, but it covers many routers on the market. If the router is not here or the default password does not work, be sure to write following query in the search engine "... router default password". Note that for the time of publication of this document may have come on the market other devices which may have other configurations.
The default IP address/password for your router should be one of the following:

Following models (and brands) use the default IP Address (192.168.1.254)

Westell DSL Modems (US ONLY)

Some Linksys Routers/Modems

3Com Routers/Modems

Billion Routers/Modems

Netopia / Cayman Gateways

Following models (and brands) uses the other specific IP Address. 

Alcatel

Alcatel SpeedTouch Home/Pro – IP Address: 10.0.0.138  - (no default password)
Alcatel SpeedTouch 510/530/570 – IP Address: 10.0.0.138  - (no default password)

Asus

Asus RT-N16 – IP Address: 192.168.1.1 - Default Password:  admin

Dell

Dell Wireless 2300 router – IP Address: 192.168.2.1

D-Link

D-Link DSL-500 – IP Address: 192.168.0.1 - Default Password: private
D-Link DSL-504 – IP Address: 192.168.0.1 - Default Password: private
D-Link DSL-604+ – IP Address: 192.168.0.1 - Default Password: private
D-Link DIR-505 – IP Address: 192.168.0.1 - Default Password: private

Netcomm

Netcomm NB1300 – IP Address:192.168.1.1
Netcomm NB1300Plus4 – IP Address:192.168.1.1
Netcomm NB3300 – IP Address:192.168.1.1
Netcomm NB6 – IP Address:192.168.1.1 - Default Username: admin -  Default Password: admin
Netcomm NB6PLUS4W – IP Address:192.168.1.1 Default Username: admin -  Default Password: admin -  Default WEP key: a1b2c3d4e5

Netgear

Netgear DG814 – IP Address:192.168.0.1
Netgear (Optus branded) IP Address:10.1.1.1

Linksys

Possible user and password combinations:
Username: admin
Password: admin

Username: Administrator
Password: admin

Username: admin
Password (empty password)

IP Address: 192.168.1.1

 

Many homes and businesses today use a NAT router to manage multiple computers and devices on a single public IP address. To explain briefly,  may exist some complication associated to NAT router, this involved to the public IP address. NAT routers take the public IP address for itself and assign local IP addresses to computers and devices on the local network, this is because all of them can effectively share the same IP address. The system works well until you want to give access to files, programs or other information to people in external Internet. When they try to connect to the computer through the IP address, you are actually connecting to the router and it does not know how to forward the connection to the appropriate equipment unless it has been informed how.
When the router communicates which device should forward a connection, it is known as port forwarding. Each application server is based on a port number through which it works. Its port number is useful to give the router the information you need to forward a connection.
First, you must determine which port the application uses and the type of connection: it can be TCP or UDP. You can usually find this information in the program settings in the help documentation or online. Certain types of programs will use a specific port that is reserved for application such as HTTP for web traffic on port 80, or SMTP for sending email on port 25.
Most modern routers comes with a built-in virtual server option which allows to define a single public port on the router for redirection to an internal address called IP LAN and private LAN port. This feature is useful for hosting online services such as FTP, VoIP Servers, Printer Servers or Web servers. In other words, and with a more practical sense, basically what you do is open holes (ports) in the firewall to allow the correct IP routing requests that are made to the router. You must then log on the router and access the settings. This process is different for each router, so you will need to find help documentation and read about how to do and how to redirect ports. The following steps can help guide you and provide information on what you will find in the router, but keep in mind this is just a starting point.

We will take as an example a router D-LINK DIR-505 model

Step 1:

Login to the router, typing the gateway IP address, for this example the IP is 192.168.1.254

Step 2:

Once we have logged in we must go to 'Advanced' tab

Step 3:

The first page we found is virtual server configuration, there we can configure up to 8 virtual servers (DIR-505 model), select the 'Application Name' drop-down menu to get a list of predefined server types. If we select one of the predefined server types, must click the arrow button next to the drop-down menu to fill the field.

Step 4:

We can select a computer from the list of DHCP clients in the Computer Name drop down menu, or  manually enter the IP address of the computer at which we are going to open the specified port.

Step 5:

Setup the ports, there are two types of ports:
    Private Port.
        The port that will be used on the internal network.
    Public Port.
        The port that will be accessed from the Internet.
For example, if our ISP have blocked the port 80 we need to configure another 'unblocked' port, as port 8888, using the port 80 as private port and the port 8888 as public port. With this Virtual Server entry, all Internet traffic on Port 8888 will be redirected to your internal web server on port 80 at IP Address 192.168.0.1.

Step 6:

Select the protocol used by the service. Can use UDP, TCP or both.  To specify any other protocol, select "Other" from the list, then enter the corresponding protocol number in the Protocol box.

Step 7:

Check the left box to activate or deactivate the entries and click the 'save settings' button.

check

Note: It is necessary to note that configuring virtual servers on your home  or office network is a exposure of your devices to attacks by outsiders, due this  you have to take all necessary security actions to protect your network from risks.