Even with a wireless network, something can sometimes go wrong. The signal is not strong enough or it occasionally drops out. Analyzing your WiFi is then necessary, but how do you do that? And how do you find out which data the apps on your (Android) smartphone send? We get started with some free analysis tools and techniques.
You probably recognize it: one moment you have a good wireless network connection, the other time you don’t. Or in one place it goes smoothly, but in another it is a lot less, even with a wireless access point nearby. What is the cause? Is the signal from your router not strong enough, does something go wrong when roaming, is the router not positioned optimally, is there interference from neighboring networks?
Detecting the exact cause is not always easy, but with the right tools you can at least troubleshoot more specifically. We’ll focus on a few Windows tools in this article, as well as a few Android apps. In addition to troubleshooting, we also pay attention to the data itself: which data actually goes through the air?
01 WinFi
Several free tools exist to analyze and monitor wireless networks, such as Acrylic Wi-Fi Home, NetSpot Free and WifiInfoView.
We are especially impressed by newcomer WinFi given the extensive and technical information the tool provides. You can do the program here to download. Among other things, we will use it to check the signal strength of our wireless network, to determine which access point our client is connected to, which Wi-Fi channels you best set and how much data goes through such a channel.
As soon as you launch the tool, it scans for wireless networks and lists them. The network you are actually connected to will have a different color.
02 Scan
You can choose between 2.4 GHz, 5GHz and ALL. Keep in mind that some routers are of the “simultaneous dual band” type and can therefore transmit simultaneously on both frequencies.
By default, WinFi renews the scan every three seconds, a process that you can always pause. If you prefer a different scanning frequency, click Settings, Open Data Grid and adjust the frequency Scan interval (from 0 to 10 seconds). Here you will hear that Unreachable APs (access points) are no longer displayed after three minutes. You can adjust the duration, but also Dont Show or Dont Remove select. We recommend that you tick the box Show ToolTips leave it: you will get useful explanations when you move the mouse pointer over a column name.
03 Information
You decide which columns you will see exactly, depending on the chosen view. You set that at the top right, for example Default View, Basic or Pro. There are also many more informative columns available. In the right pane, click + Columns and place a check mark next to the column you want to make visible. Columns can be repositioned with a simple drag. You can also place a certain view in a profile for quick access afterwards. Open the view button, choose Create New Profile and fill one at the top Profile Name in.
04 Signal quality
How can you use WinFi to investigate a problematic network connection? To start, check the signal quality of your router or access point. There are several columns that can give you information.
Signal Quality is the least technical and expresses the signal quality as a percentage: from unworkable (0%) to excellent (100%). Realize that even a high percentage does not necessarily offer guarantees for a high data transfer. This is because there may be signals that are interfering with your own WiFi network, coming from other wireless devices such as a baby monitor, or from a neighboring network (see also section 6 “Channel selection”).
If you receive a weak signal and you are still close to an access point, check whether roaming is working and whether your device is actually connected to that access point. It is best to make the column for this BSSID visible (Basic Service Set Identifier), as it contains the unique MAC address of your access point’s network adapter.
Also the column Channel Utilization Graph gives you useful information. It indicates how intensively the active channel of your router or access point is used. If this percentage is 75% or higher, there is very heavy traffic – for example, because multiple clients address your router, which can lead to slower transfers, interruptions or data packets being lost. You can further investigate the latter with a data sniffer such as Wireshark (see also paragraph 12 “Package sniffer”).
05 Signal versus noise
If it is a bit more technical, make sure to make the columns RSSI and SNR visible. RSSI stands for Received Signal Strength Indicator and is expressed in negative dBm values ​​(decibel-milliwatts). The higher the negative dBm value, the weaker the signal. With a value between -70 dBM and -100 dBM, you no longer have to rely on a stable network connection. In many cases it helps to move closer to your router or access point with your mobile device (see also paragraph 8 “Site survey”).
Closely related to RSSI is the column SNR (Signal To Noise Ratio). This value is expressed in decibels (dB) and the higher the value, the better the Wi-Fi signal exceeds any background noise. A figure below 25 dB indicates a weak WiFi signal.
WinFi also presents both values ​​beautifully graphically. Open the tab for this Dashboard (or Signals) in the bottom window. You can read the maximum, minimum and average values ​​of the selected network here. In addition, there is the UTILValue (Channel Utilization), the LINKvalue (an indication of the signal quality) and the RATE (indicates the physical maximum available transfer speed of your router).
06 Channel selection
So WinFi gives you an excellent picture of the signal quality of your wireless network. If you are close to the active router and you still have (interrupted) transfer problems, you may be dealing with a jammer. Especially when you use the 2.4GHz band, it is best to check the channel selection. After all, here the number of actually deployable channels is usually limited to 11, with neighboring channels also overlapping each other considerably. That is why you preferably set the channel of your router to a channel that is at least five numbers away from that of neighboring networks.
In practice, this usually means a choice between channels 1, 6 or 11. In the column CH (Channel) you can read the used channels and in the graph you also get a nice drawing on the tab Spectrum. If there is indeed (too much) overlap with another network, it is best to switch to a different channel in your router.
07 Monitoring
On the tab History in the graphical window you get an overview of recently determined results both to RSSI, SNR, Signal as UTIL to.
WinFi automatically keeps track of all scan sessions and you can reach this via the button Archive. You just need to select the desired session and the button Replay pressing, after which WinFi plays the various scan moments in succession; at the top you will see a counter and you can pause playback at any time. During playback, you can view each part of the interface and check which values ​​fluctuate.
Good to know: right click on a network name to copy the detected data in various formats to the clipboard or to export it as a Pcap file. You can pick up the latter in a package sniffer such as Wireshark.
08 Site survey
Although you can also use WinFi to optimally position your router, you are better off with a specialized program for a real site survey. As you walk around with your laptop, such a tool continuously registers the signal strength of your wireless network and plots the results in a so-called heat map. This way you quickly find out where the coverage is below par. You can then move your router or install an additional access point.
Ekahau Heatmapper is just about the only free site survey tool we know. When starting up, you prefer to import a floor plan of your house or workspace via I have a map image. Then you walk around with your laptop and click on all relevant locations where you are at a given moment. Click the right mouse button once you’re done with this. When you then click on a network name on your map, you can see how strong the wireless signal is by means of color codes.
You can also check what happens if, for example, you reposition (the antennas of) your wireless router.
09 Device detection
Suppose you have shielded your wireless network (at least) with wpa2 encryption, but you still suspect that an unauthorized device occasionally connects to your network. A monitoring tool like it for free Wireless Network Watcher (Dutch language file available) can help you.
The program immediately scans your network and lists the connected devices, including IP and MAC address, device and brand name. Through Advanced options indicate the desired (wireless) network adapter, set the scanning frequency and determine what to do when the tool detects a new device in your network, such as playing a sound or executing a command.
Softperfect WiFi Guard (available for Windows, macOS and Linux; from 19 euros) you can also send an email with the ip and mac address of newly detected devices, but in the free version the display is unfortunately limited to five devices.
10 Mobile analysis
It can also be useful to walk around with your smartphone and read the signal strength of the detected wireless networks “live”. This becomes difficult on iOS because Apple’s API restrictions do not just allow you to scan networks and retrieve information. In the Apple App Store there is the free Network Analyzer Lite (by Techet), but this app gives you little more than the name, IP and MAC address of the devices that are connected to your network.
Fortunately, you will find useful apps in the Google Play Store. One of the better is WiFi Analyzer (from farproc). Tap the eye icon and choose Channel chart to read the channel used as well as the signal strength for each network (in -dBm values). Open Channel rating to request the optimal channel for the selected network.
11 Package analysis
With WiFi Analyzer you can determine the signal strengths and channels of wireless networks, but what if you also want to take a look at the data packets themselves? Later in this article, we do that using a PC that acts as a hotspot. You can also do this directly on an Android device, with the free app Packet Capture (from Gray Shirts). The app first installs a local VPN service and ensures that all data traffic passes through it, which makes viewing possible.
Install the app and launch it. Tap the arrow button and confirm with Allow / OK to set up a VPN connection. The scan starts immediately. Tap such a scan session to see the data packets collected; you get even more details if you select such a package yourself.
To also capture encrypted https traffic, open Settings in Packet Capture and choose Status. Confirm with OK to install a self-signed vpn certificate. Then open the settings of your device and choose Network and internet / VPN. Tap the gear icon at Packet Capture and activate Always-on VPN.
Keep in mind that you cannot use another VPN server as long as Packet Capture is active.
12 Package sniffer
Sniffing and analyzing data can be done much more thoroughly with a free tool like Wireshark. We would like to tell you that this program comes into its own in the hands of an advanced user who is well versed in network protocols. We limit ourselves here to a modest start.
Install the tool, including the latest Npcap driver. Then start up Wireshark: that shows the available network interfaces, after which you select the – wireless – interface.
With a double click you start the scan. Choose to end it Capture / Stop. Then select Capture / Options and make sure that your wireless network adapter has a check mark next to it Promiscuous. You also tick the box for an extensive analysis Monitor Mode. In this mode, not only the mere data is picked up, but also all management and control information. The problem is that not all wireless network adapters can handle this: see www.tiny.cc/wifiadap (columns Monitor mode and Capture works).
Furthermore, if you also want to receive data from other wireless devices in your network, you can set your PC as a mobile hotspot and have your wireless devices connected to it so that Wireshark can also pick up that data (see also the box “Hotspot”).
Hotspot
Setting up a wireless hotspot in Windows 10 is basically easy. Press Windows Key + I and choose Network and internet. In the left pane, select Mobile hotspot. Right click edit and fill you up Network name and Network password in. Confirm with Save. Choose the network connection that you will share via your mobile hotspot and set the switch to the top On. If all goes well, your wireless devices just need to connect to the set network.
If it doesn’t work with this built-in function, which can indeed be a bit silly, you can also do it with Command Prompt commands. You will find the necessary instructions, among other things here.
Network Management Course
To run your home network – and all connected devices – at full speed, we offer the Tech Academy course Network management for the home On.
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