[HOW TO] Diagnose Wireless Issues
There have been a lot of questions regarding the stability of wireless connections over the last few months/years. Because of this I figured it would be helpful to many if we had a thread that outlined the starting points for diagnosing wireless issues, I will also include some background information which you may or may not wish to read - it will not essentially help problem solving but it might help understanding.At present this thread is only dealing with Windows software. If any Mac users are reading this and wish to offer input then please let me know.
Also please let me know if anything needs correcting or editing in any of these posts. Thanks.
The biggest problem is that wireless networking has become very common as well as popular and along with this has come the expectation that it will just work, sadly this is not always the case. For wireless networking to work, and to work well there are a number of requirements that must be met.
Background information.
As I said I will share a little background on the key points to wireless networking and the technologies involved, reading this part will mean that you will be on the same page as me when explaining things further on, but as I said before it's not essential reading.
There are 3 main types of wireless networking that you should know about, they are: B, G and N. Wireless networking usually communicates in the 2.4, 3.6 and 5 GHz frequency bands but mostly 2.4. Most networks offer 11 channels but sometimes you can get up to 14. The channels are divisions of the 2.4 GHz range, these channels overlap each other though. Channel 1 uses the lowest frequency and it increases along with the channel number - there are 3 main channels which do not overlap with each other these are 1, 6 and 11 - because of this these are the three most used channels.
The range of wireless networking equipment should never be taken at face value, the figures that are specified are generally perfect world and they do not give for the various types of interference which almost all users will have such as Electromagnetic interference (EMI), Walls and channel bleed to name some.
Wireless security is not something I plan on covering here but I figure it's worth mentioning that WEP security is easily hacked and some versions of WPA can also be hacked - contrary to what appears to be popular belief that WPA is 100% safe.
Common problems.
There are a number of common problems that get raised and they are:
1) Connected but not working - usually this is a case of not actually having network access.
2) Unable to connect - usually this is a case of configuration, passwords are case sensative and sometimes you might have WPA2 instead of WPA1.
3) Slow network - usually this is down to interference, low signal strength or access point saturation.
4) Intermittent connection - this is usually down to the same points as above but mostly interference.
Free tools for testing.
I will be going into detail on how to use inSSIDer after this post and may include details for the other apps at some point in the future.
Windows Tools.
inSSIDer - This is a tool that many members here will mention if someone has a wireless issue.
Chanalyzer - This is a tool brought to you by the same people who make inSSIDer, this app gives you visualisations of your wireless landscape.
Xirrus Wi-Fi Inspector - This is a tool which is very similar to inSSIDer but provides a different layout, the information is similar but some people prefer to use a different layout.
Ekahau HeatMapper - Slightly more advanced is HeatMapper which can provide you with a good site audit of signal strength and access points on a graphic map of your site. Not really very useful for home use but worth mentioning.
Mac Tools.
KisMAC - A free Wi-Fi scanner app, often recommended here for Mac users.
AirRadar - Used to be free but now I believe it is an app you buy, old versions may still be free although I do not know. Using inSSIDer.
I am going to assume that you have downloaded and installed inSSIDer and are ready to run the program.
Depending on the version of the software you may see a different screen to that of which I have screenshots for at the moment, I will try and update according to any new versions shortly, but the information within should be the same.
So here is the first screen we should see:
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The first thing you should look at is at the top, before scanning you will see the drop down menu with network adapters, for this you obviously need to select your wireless network adapter, then click the Start button. Once you have done that you should start to get something that looks a little like what I have posted.
First you see a list of surrounding networks with details of them, then under that you get 2 graphs, the line graph on the left shows historic data for your signal strength and the one on the right shows current strength for all selected networks.
If you do not wish to see all of the surrounding networks in the graphs you can untick them with the boxes in the list view.
List view.
Okay so now you have a load of information on the screen but you don't really know what it is or what you should do with it...
The columns:
1) MAC Address - This is the physical address of the router/access point, it is a unique address that identifies the device. This is of little importance to our diagnosis.
2) SSID - This is the name of the network broadcast by the device - this helps you identify your network.
3) Channel - This is the channel that you are using.
4) RSSI - Received Signal Strength Indication note that the Wikipedia article conflicts with the information within inSSIDer, don't worry about this. This column is signal strength, the lower the number the stronger the signal; -48 is stronger than -93. Signal strength ranges between around -30 and -100.
5) Security - This shows what security type is being used, WPA, WEP, WPA2 and so on.
6) Network Type - Does what it says on the tin, not an important factor here.
7) Speed - Shows what speed the device is showing - most will be set to Automatic speed but some may be forced to certain speeds.
8) First/Last Seen - Again, self explanatory, these signal when you first and last saw the network while scanning.
I have put 3 of the above in bold as these are the ones which we will concentrate on, these are: SSID, Channel and RSSI.
First you need to ensure you are looking at your network, so you will need to look at the SSID to find that, once you have located that then look at your Channel and compare it to what the surrounding networks are using, if there are a lot of networks on the same Channel as you then you might be better off changing your channel to a different one. As previously mentioned try stick to 1, 6, and 11 as these have no overlap with each other. You can usually change these settings very easily in your router configuration page - if you get stuck then someone will help you providing you state the make and model of your device.
Also you will want to look at the RSSI column - if you have connection problems in certain areas of your house try running the scan and checking the RSSI in various areas and see how your signal drops or changes in different places.
If you are asking for help with wireless problems after this, please include details of your testing so that whoever is helping you can see that you have tried the basics and can then try and figure out what might be the problem based on your results. Thanks for starting this, Iccz, and I really hope this thread takes off.
As a wireless user with Windows, OSX, and Android clients as well as games consoles (big family), we get all sorts of connectivity problems. Trouble is, it's hard to know where to start with diagnosing the source of the problems.
I'll be trying all the tools you mention there, but it would be good to have some recommended websites covering the theory and any top tips (possibly including DHCP which seems to be implicated in our setup). Thanks for the input, Joe.
I will definitely be adding some links with more information at some point, I just wanted to get the thread up and running as a starting point, I'm sure the more technical members will throw some corrections and changes my way to help it become a more complete guide data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 1.Use inSSIDer or kisMac on a PC that supports them to eliminate ChannelConflict. Fixing it for one set of devices fixes it for all.
2.DHCP problems will,affect wired as well as wireless devices equally.The rule of thumb for amateurs is to leave DHCP to run you IP addressing unless you know what you are doing.More amateurs get themselves into trouble using fixed addressing than get themselves out. Thanks beerhunter.
The laptop I'm running inSSIDer on may be particularly insensitive, but it can only see our own router. My Nokia tablet on the other hand can often see half a dozen. Thing is, even if inSSIDer did show all these SSID's, I'm not sure how best to avoid overlap. Iccz's notes suggest using channels 1, 6 or 11 as these don't overlap. But IIUC it is only true that these channels don't overlap each other - they do overlap the in between channels. Channel 6, for example, overlaps every channel from 2 through 10 (source: Wikipedia). It seems there is no chance of completely avoiding overlap.
Why so? This was going to be my next tactic. Surely it is straightforward to map a dedicated IP address to each MAC address. Can you expand on what the pitfalls are? The point about 1, 6 and 11 is that they do not overlap each other so are not going to conflict with each other, these are the 3 channels that are set to default values on most gear, 6 is usually the default but sometimes 1 or 11 are used too. The point is if you neighbours all use 6, then using 2 will not avoid it, but it will include anything from neighbours using 1... where as if you move to 1 you are just contesting with those on channel 1 (or perhaps someone if they are on another channel in between - which is not likely). You are absolutely correct and I was going to ask that the sticky be reworded.
They way to use the tools is to do a survey in the rooms where you will be using WiFi, at different times of day.Once you know what is going on locally, set your router to a channel that not only is not is usebut is at least two channels away from any that are.(I'd like a pound for every time that I have keyed that on these forum.)
If you can't find that happy place, then you may need to think of using 802.11n in the 5 gHz band, (Until that fills up.data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7), or wired Ethernet, or HomePlugs. Hence the reason we've produced a sticky data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7If you'd like to suggest a re-wording the overlap paragraph, I'm sure Iccz would welcome the input As above, I'm open to suggestions. All I have ever read on the subject specifies these 3 channels as "non-overlapping" although a closer look seems to make 1, 7 and 13 non-overlapping in Europe - but I don't believe this is always the case. I have changed it so that it reads they do not overlap with each other for now, but any other suggestions are welcome data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7