What are common problems that need to be solved

WLAN problems solved: connection errors, crashes, authentication problem and much more.

David Wolski, Christian Löbering, Panagiotis Kolokythas, Roland Freist

Are you unable to access your own WLAN due to an authentication problem? The wireless network is way too slow? Stay calm: With our tips you can solve the most common WiFi problems.

EnlargeSubsequently purchased adapters for the USB port make older PCs and notebooks fit for newer WLAN standards and also improve reception.

Wireless networks have a significant disadvantage: When they are set up, it is initially not foreseeable how fast the WLAN will ultimately be or whether it will even find a stable connection.

Because the effective data rate depends on too many factors such as the 802.11 standards used, the distance to the WLAN router or the access point, the antennas, the hardware used and disruptive influences. Frustration arises when new devices also have poor reception or suffer from disconnections.

See also:10 tips for a fast and stable WiFi

If a WLAN connection cannot be established, the devil is often in the details. Common mistakes are, for example, incorrectly set encryption settings.

We describe the most common causes of connection and speed problems in the WLAN and give tips for diagnosis and problem solving.

Table of contents - this is how you can solve typical WLAN problems quickly

Solve WLAN authentication problem

Certainly one of the most common mistakes when connecting to WiFi is a reported authentication problem. The causes for this can be varied. However, the problem can usually be resolved with a little systematic approach.

The authentication problem indicates that the client device and router can see each other or receive data from each other, but the connection is not established because both devices do not recognize each other. This can occur equally with the Android router or PC router connection. How to solve it:

  • First, check that you have entered the correct WiFi password. For example, the letters "O", "l" and "I" are often confused with the digits 0 and 1. If you have access to the router with another device (or can temporarily plug in a LAN cable), it is best to read out the WiFi password on the router. With the Fritzbox, open the interface http://fritz.box, select "WLAN -> Security -> Encryption" and copy the WLAN network key to the clipboard or into a text editor such as Notepad. If you choose a font such as "Courier New", the characters can be easily distinguished.

  • Of course, it is also important that you use the same encryption for the router and client device (tip 4). Here, too, a look at the router interface helps - with the Fritzbox also under "WLAN -> Security -> Encryption". Select the same encryption set in the router on the client device (usually WPA2)

  • Another cause of the problem can be that a Mac address filter is set in the router. The Mac address is a number that is unique worldwide for each network adapter. However, if only certain Mac addresses have been activated on the router, you will not be able to connect to another. It is then enough if you have exchanged the network card or have a new WLAN stick in use. To check and deactivate the filter, select, for example, "Wlan -> Security" again on the Fritzbox interface and activate "Allow all new WLAN devices" there.

  • If none of this helps, you should try restarting the router. To do this, unplug the router for a few seconds and then plug it in again. The boot process can then take a few minutes. You should also just restart your client device.

  • If the problem persists, you should try to delete all WLAN profiles stored on the client device and then reconnect. To do this, open a command line window (cmd.exe) and enter the following commands there:

instead of "Profile Name", either enter the name of a WLAN profile that was determined with the first command. Or you can type * (without the quotation marks) to delete them all. On Android, you can simply delete WiFi profiles via the settings.

Set up the router optimally

Walls, doors and also furniture impair the electrical field of the WLAN and can cause radio shadows. The typical rod antennas on WLAN routers work as omnidirectional radiators. A less well-lit area remains in the vertical axis with this type of antenna. As a result, these antennas provide good coverage for a level floor, for example, but radiate less in height and depth.

In these scenarios, it is worth moving the wireless router and realigning the antennas, because even small changes can have major effects. Meanwhile, measure the signal strength of the WLAN on the notebook. The freeware tool Wireless Netview is again suitable for this. In addition to the average signal strength, this utility always shows the current signal strength without delay. Detailed plans of the radio coverage in your own four walls can be created with the freeware Ekahau Heatmapper, which is also available for download with an e-mail address. In connection with a notebook / ultrabook and Windows you can easily create a so-called heat map. A map of the reception quality is quite precise and clear if you have a floor plan of the premises. If not, just draw a rough plan in a graphics program or scan in a floor plan. In Ekahau Heatmapper you read the image file with "I have a map image". Alternatively, you can also work with a predefined grid.

Optimize antennas

Antennas are an often overlooked factor when optimizing a WLAN. Most routers have external rod antennas that can be rotated in different directions. These models emit their signal at a right angle. You will get ideal reception with the client when its antenna is aligned in the same way as that of the access point, i.e. normally vertical. However, since the signals are deflected by walls and other surfaces, there may be significant deviations from this rule. The only thing that helps is trying out how the reception is best. This can be measured with software such as Homedale or an app such as Wifi Analyzer for Android.

The WLAN standards 802.11b and g only ever use one antenna. Nevertheless, appropriate routers often bring two with them and then always use the one that offers a higher connection strength. You should therefore rotate these antennas in different directions. 802.11n can use up to three antennas in parallel, each of which transmits a maximum of 150 Mbit / s. However, in order to achieve the maximum theoretical speed of 450 Mbit / s, the WLAN device must also be equipped with three antennas. Due to their form factor, smartphones or USB adapters usually only have an antenna, which means that they can at best achieve 150 Mbit / s.

The newer models of the Fritzbox work with internal antennas that radiate the WLAN signal in an approximately spherical shape. Depending on the installation location, a lot of transmission power is lost. If the router is placed in a corner, you can try to direct the signal in the desired direction using metal foils or sheets. Alternatively, the Frixtender company offers kits with external rod antennas for the various Fritzbox models, which significantly increase the signal strength, at prices between 20 and 35 euros. Very good: You can also find the installation instructions on the manufacturer's website.

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