Even with a wireless network, things can sometimes go wrong. The signal is not strong enough or it drops out occasionally. 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? Let's get started with some free analysis tools and techniques.
You probably recognize it: one moment you have a good wireless network connection, the next moment 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 your router's signal not strong enough, is there something wrong with roaming, is the router not optimally positioned, is there interference from neighboring networks?
Finding the exact cause is not always easy, but with the right tools you can at least troubleshoot more specifically. We focus on some Windows tools in this article, but also take a look at a few Android apps. In addition to troubleshooting, we also pay attention to the data itself: what data actually travels through the ether?
01 WinFi
There are several free tools to analyze and monitor wireless networks, such as Acrylic Wi-Fi Home, NetSpot Free and WifiInfoView.
We are particularly impressed with newcomer WinFi given the comprehensive and technical information the tool provides. You can download the program here. We will use it, among other things, to check the signal strength of our wireless network, to find out which access point our client is connected to, which WiFi channels are best set up and how much data passes through such a channel.
Once 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 2.4GHz, 5GHz and ALL. Keep in mind that some routers are of the 'simultaneous dual band' type and can therefore broadcast on both frequencies simultaneously.
By default, WinFi refreshes the scan every three seconds, a process you can pause at any time. If you prefer a different scan frequency, click Settings, Open Data Grid and set the frequency at Scan interval (from 0 to 10 seconds). Here you will find out Unreachable APs (access points) are no longer displayed after three minutes. You can adjust the duration, but also don't show or Don't Remove select. We recommend that you check the box Show ToolTips you will get useful explanations when you hover the mouse pointer over a column name.
03 Information
You decide which columns you see exactly, and that depends on the chosen view, among other things. You set it in 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 next to the column you want to make visible. Columns can be repositioned with a simple drag movement. You can also place a certain view in a profile so that you can quickly call it up afterwards. Open the view button, choose Create New Profile and enter a at the top Profile Name in.
04 Signal quality
How can you use WinFi to investigate a problematic network connection? To get started, 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%). Be aware that even a high percentage does not necessarily guarantee a high data transfer. There may be signals that disrupt your own WiFi network, originating 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 near an access point, check that roaming is working and that your device is actually connected to that access point. It's best to make the column for that too 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. This indicates how intensively the active channel of your router or access point is used. If this percentage is 75% or higher, then there is very busy traffic – for example because several clients are accessing your router, which can lead to slower transfers, interruptions or the loss of data packets. 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's just a little more technical, make sure to make the columns too 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 count on a stable network connection. In many cases it helps to move your mobile device closer to your router or access point (see also section 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 WiFi signal comes out above any background noise. A number lower than 25 dB indicates a weak Wi-Fi signal.
Incidentally, WinFi also presents both values nicely graphically. To do this, open the tab Dashboard (or signals) in the bottom window. Here you can read the maximum, minimum and average values of the selected network. In addition, there is the UTILvalue (Channel Utilization), the LINKvalue (an indication of the signal quality) and the RATE (indicates the maximum physical transfer rate available from your router).
06 Channel selection
WinFi therefore gives you an excellent picture of the signal quality of your wireless network. If you are close to the active router and you are still dealing with (aborted) transfer problems, then you may be dealing with a jammer. Especially when you use the 2.4GHz band, it is a good idea to check the channel selection. After all, here the number of channels that can actually be used is usually limited to 11, with neighboring channels also overlapping each other considerably. Therefore, it is preferable to set your router's channel to a channel that is at least five numbers away from neighboring networks.
In practice, this usually means a choice between channels 1, 6 or 11. In the column CH (Channel) you read the used channels and in the graph you also get that nicely drawn on the tab Spectrum. If it turns out that there is (too much) overlap with another network, it is best to switch to another 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 if UTIL up.
However, WinFi automatically keeps track of all scan sessions and you can reach them via the button Archive. All you have to do is select the desired session and click the Replay to press, after which WinFi plays the various scan moments one after the other; at the top you will see a counter and you can pause playback at any time. During playback, you can view every part of the interface and see which values are fluctuating.
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 then retrieve the latter in a packet sniffer such as Wireshark.
08 Site survey
You can also use WinFi to optimally position your router, but for a real 'site survey' you are better off with a specialized program. While you are walking around with your laptop, such a tool continuously registers the signal strength of your wireless network and then plots the results in a so-called heat map. This way you can quickly find out where the coverage is below par. You can then move your router or install an additional access point.
Ekahau Heatmapper is pretty much the only free site survey tool we know of. When starting up, you preferably import a floor plan of your home 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. Right click once you are done with this. When you then click on a network name on your map, you can see how strong the wireless signal is based on color codes.
You may want to 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 such as the free Wireless Network Watcher (Dutch language file available) can then be helpful.
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 scan frequency and determine what should happen when the tool discovers 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) can also send you an email with the IP and MAC addresses of newly detected devices, but in the free version the display is unfortunately limited to five devices.
10 Mobile Analytics
It can also be useful to walk around with your smartphone and read the signal strength of the detected wireless networks 'live'. On iOS, that gets tricky because Apple's API restrictions don't 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 connected to your network.
Fortunately, you will find useful apps in the Google Play Store. One of the better ones is WiFi Analyzer (from farproc). Tap the eye icon and choose Channel chart to read the channel used as well as the signal strength (in -dBm values) for each network. Open Channel Rating to request the optimal channel for the selected network.
11 Packet Analysis
WiFi Analyzer allows you to 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'll do that using a PC that acts as a hotspot. It can also be done directly on an Android device, with the free Packet Capture app (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 on such a scan session to see the captured data packets; 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 your Status. Confirm with OK to install a self-signed VPN certificate. Then open your device's settings and choose Network & Internet / VPN. Tap the gear icon at Packet Capture and activate Always On VPN.
Keep in mind that you cannot use another VPN server while Packet Capture is running.
12 Packet Sniffer
Sniffing and analyzing data can be done much more thoroughly with a free tool like Wireshark. We are happy to tell you that this program comes into its own in the hands of an advanced user who is well aware of network protocols. We limit ourselves here to a modest introduction.
Install the tool, including the latest Npcap driver. Then start Wireshark: that will show the available network interfaces, after which you select the – wireless – interface.
Start the scan with a double click. To end it, choose Capture / Stop. Then select Capture / Options and make sure your wireless network adapter has a check mark next to promiscuous. For an extensive analysis, also tick the box 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 collect data from other wireless devices in your network, you can set up your PC as a mobile hotspot and have your wireless devices connect 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 on To process and fill you 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 at the top to On. All you need to do is connect your wireless devices to the set network.
If it doesn't work with this built-in function, which can indeed be petty at times, you can also do it with Command Prompt commands. You will find the necessary instructions here.
Network management course
To keep your home network - and all connected devices - running at full speed, we offer the Tech Academy course Network management for the home.
