Introduction This is a large document, but there is a lot to cover on this subject. Plus where any configuration changes are outlined, this covers just about all TalkTalk routers, which in itself contributes greatly to the length of this document. If you are having intermittent breaks in your signal, or are getting a much lower speed all the time on Wi-Fi devices compared to wired ones, then you may be suffering from interference on your Wi-Fi channel. In addition to this & just as important is where the router is situated within the property. I have produced another guide on Wi-Fi guidelines, if you need to know more about this, please ask for it. It is also vital to understand the router may not be the cause of your problems, it could equally be the Wi-Fi adapter in your device. Prove whether you are suffering from this type of interference, before doing anything else. Please see the section below Are you suffering from interference prove it first. Within the older frequency band for 802.11n & earlier Wi-Fi standards, the 2.4GHz band there are only three non-overlapping channels, these are 1, 6 or 11. Don't take my word for this, it is covered in these articles:http://www.metageek.com/training/resources/why-channels-1-6-11.html http://boundless.aerohive.com/experts/wlan-channels-explained.html The later 802.11n routers & wirelessly connected devices may be Dual band, in addition to the 2.4GHz frequency band, they also can use the newer 5GHz band. This suffers much less from interference, because it has a lot more non-overlapping channels than the 2.4GHz one & they do not share this band with common household items that use the same 2.4GHz radio frequency band (not 802.11 Wi-Fi). If the router & wireless devices support the newer standard 802.11ac, then that only operates within the 5GHz band. Table of contents Are you suffering from interference prove it first Changing channels - Huawei routers Changing channels HG633 / HG635 routers Changing channels - D-Link DSL routers (up to DSL-3780) Changing channels - D-Link DSL-3782 router Bandwidth, Channel Bandwidth, or Channel Bonding Other causes (not Wi-Fi interference) Page 1 of 27

Are you suffering from interference prove it first This is the easiest & best way to prove if you are suffering from interference from other Wi-Fi networks. I can help with this issue, but it depends on if your have a PC, or laptop that connects via wireless that can run a program called Acrylic Wi-Fi Home, which is a free Wi-Fi analyser for Windows. I used to recommend "inssider Home", whilst the current inssider version is excellent, it is no longer free. The freeware version is an older one, which does not fully support 802.11ac and can incorrectly display some characteristics with this newer Wi-Fi standard. Please read the section on Using Acrylic Wi-Fi Home including the section on setting it up & which screenshots I require. Note 1 : this is only available for the Windows operating system for PCs & laptops, some alternatives for different operating systems are listed within this guide. Note 2 : Acrylic Wi-Fi Home is an 802.11 Wi-Fi analyser, it cannot detect RF interference from non 802.11 devices that operate at 2.4GHz. Continued on the next page. Page 2 of 27

Acrylic Wi-Fi Home This free analyser for Windows (alternatives for other operating systems are listed below), it can be downloaded from the vendor's website:https://www.acrylicwifi.com/en/wlan-software/wlan-scanner-acrylic-wifi-free/ Once installed you must first put Acrylic into Advanced mode. This is done by clicking on the menu icon near the top right & click to turn on advanced mode as shown:- Then the analyser will start running, if you wish to stop it, because you have made some changes to your router, click on the stop icon:- To start the trace running again click the start icon:- Continued on the next page. Page 3 of 27

Using Acrylic Please start by maximising the Acrylic window, otherwise screenshots you take of the display will often be too small to read & some information may be obscured requiring scrollbars to see everything. Do not use a camera to take a picture of Acrylic, that will not give the quality required to read the text information within this analyser display. Once running in Advanced mode it will look like the example below. Please can you click on your router's network name (SSID) in the SSID list in the upper pane? If the problem is on the 5GHz band, then select that SSID. This will allow me to see your network much more clearly in other panes:- Let the trace run for about 5 mins during the time period when you have the problem. All screenshots can be taken with the Windows Snipping Tool if required (Windows 7 onwards), or another utility of your choice. Screenshots required are listed over the next page. Page 4 of 27

Screenshots required If running Windows 7 or later, you can use the inbuilt Snipping Tool to take the screenshots. Unlike inssider you cannot see everything in one go with Acrylic, so please can you get me screenshots of all of the displays listed over the next few pages, by clicking on the tabs across the lower part of the window. Please always get a screenshot of the complete program, so as I can see both the AP list at the top & the chosen tab at the bottom. Please do not forget to highlight either the 2.4GHz, or 5GHz SSIDs (network names) in the top pane, as appropriate. Signal Strength Make sure that the time that the trace is running for covers the time period where the problem occurs. Get one screenshot with your 2.4GHz network highlighted & another with your 5GHz network highlighted (if appropriate). Continued on the next page. Page 5 of 27

Network Quality Get one screenshot with your 2.4GHz network highlighted & another with your 5GHz network highlighted (if appropriate). 2.4GHz APs Channels (highlight your 2.4GHz network for this screenshot):- 5GHz APs Channels (don't forget highlight your 5GHz SSID for this window):- Page 6 of 27

Send screenshots to me To do this, please insert them all via the Photos icon on the editor's toolbar of your reply:- Each one will probably be around 250K in size for a.png file and in the Photos upload section in the forum, please ensure the size is set to Large :- Alternatively, you can PM me, if you do, please can you also provide a link in there to your thread, to help me find it more easily. When I see your screenshots, I made need some others depending on what the first set of them show. Page 7 of 27

Alternative Wi-Fi Analysers If you do not have a Windows PC that can run Acrylic, here is a list of some alternatives, you would need to get similar screenshots as listed above with Acrylic. OS Analyser Website Windows 10 Phone WiFi Analyzer by Matt Hafner http://www.matthafner.com/wifianalyzer Android WiFi Analyzer by Farc https://play.google.com/store/apps/details?id=com.farproc.wifi.analyzer&hl=en_gb Apple Netspot https://www.netspotapp.com/ The next few pages give a brief overview of these alternative analysers & the screenshots I would require from them. Continued on the next page. Page 8 of 27

Windows 10 Phone I will need to know which network name (SSID) is your one. The software works best if the WiFi network is connected. First make sure that the Connected tab is active to get an overview of your network & take a screenshot:- Page 9 of 27

Next click on the Analyze tab & choose which WiFi band at the bottom right. Please collect screenshots each of the screens shown over the next few pages, taking one of each for the 2.4GHz band & another for the 5GHz band (if your device supports both bands). Channel display:- Continued on next page. Page 10 of 27

Then switch to the signal strength/time display via the icon bottom right & let the analyser run for a few minutes & take another screenshot:- Then click the Networks tab at the top & set to detailed view by this icon in the bottom right of the display:- Continued on next page. Page 11 of 27

Finally take a screenshot of this view (you may have to take a couple of screenshots to include all networks):- Page 12 of 27

Android I will need to know which network name (SSID) is your one. Please get screenshots (most Android devices can take a screenshot with simultaneous pressing of the power & volume down keys, but some require volume up, not down) of these views outlined over the next few pages. Please collect each of them for the 2.4GHz band & then for the 5GHz band (if your device supports both bands). Switch between 2.4 & 5GHz bands To switch the displays in this analyser between the two Wi-Fi bands, tap the top left of the display where you will sometimes see a 2.4GHz label, this will change it to display the 5GHz band:- Channel graph Continued on the next page. Page 13 of 27

Time graph (shows signal strength against time) Channel rating AP List Page 14 of 27

Apple Netspot can be used, which is free apparently. I do not have any Apple products & thus cannot produce any screenshots. Screenshots required:whatever ones are available on this analyser that match the type of ones documented with the analysers for the previously documented OS. Page 15 of 27

Log on to your router Open a web browser (e.g. Internet Explorer, Mozilla Firefox & Google Chrome etc) and then enter this address in the address bar - http://192.168.1.1 At the admin username & password, enter the logon credentials. Unless you have changed this, the default is normally:username : admin password : admin On the HG633 router, this uses it's own unique password, see the label on the rear of the router for this:- Each D-Link DSL-3782 also has its own unique logon password, which is also documented on the rear label:- Page 16 of 27

Changing channels - Huawei routers (not HG633/635) Log into the router, then go into Advanced mode then go to:basic > WLAN Look at the option called Channel & try one of the ones suggested previously and click submit. Page 17 of 27

Changing channels - Huawei HG633 & HG635 routers Before doing this it is best to change the network names (SSIDs) of the 2.4GHz & 5GHz bands. This will make it much easier to see which band you have connected to. Log into the router, select on the "Customise my Wireless Network" icon. You can then change them. One recommendation is to append "5G" to the end of the Wireless 5GHz SSID so that it looks something like:- (TALKTALKXXXXXX5G). To change the channel, click on the "Home Network" tab at the top. Click on "Wireless Settings" down the left. Scroll down the page to "Advanced Settings" & expand that if minimised. There you will find the channel setting, one for the 2.4GHz band and another further down for the 5GHz band. This is the one for the 2.4Ghz band:for the 2.4GHz band use channels 1, 6 or 11 and for the 5GHz band use channels 36 48. Note 1: in some rare cases, after setting the 2.4GHz channel to a dedicated number, some devices can no longer detect the network name (SSID). If this is the case, also in the "Advanced Settings" section, set the 802.11n bandwidth to 20MHz and the 802.11n guard interval to Short in the 2.4GHz band. You may also need to set the 802.11n/ac guard interval to Short in the 5GHz band as well. Note 2: Some devices can no longer detect the network name (SSID) in the 5GHz band if you use a channel higher than 48. This is a limitation of the network adapter in the connected device, it is not a problem with the router. Page 18 of 27

Changing channels - D-Link Routers (prior to DSL-3780) Log into the router, then click the Setup tab at the top, then Wireless Setup on the left hand side. Then click the Manual Wireless Network Setup button. In the resulting screen, untick the Enable Auto Channel Scan option and then change the Wireless channel option to channels 1,6 or 11. DSL-3780 Go to:advanced Wireless > WLAN Performance Page 19 of 27

Changing channels D-Link DSL-3782 This router is different from the older D-Link routers supplied by TalkTalk. It is a dual band (2.4GHz & 5GHz) router hence if required to change a channel you need to make sure that you do it on the correct band. Login to the router & go to:settings > Wireless (Wi-Fi) Then click on the Advanced settings link for either the 2.4GHz or the 5GHz band. By default the channel is set to Auto, before you can change the channel you must first disable this by sliding the Auto Channel switch to Disabled :- To set to channel 6 for example:- The principal for changing channels in the 5GHz band is identical to that above, except the channel numbers are different. For the 2.4GHz band use channels 1, 6 or 11 and for the 5GHz band use channels 36 48. Note: Some devices can no longer detect the network name (SSID) in the 5GHz band if you use a channel higher than 48. This is a limitation of the network adapter in the connected device, it is not a problem with the router. Page 20 of 27

Bandwidth, Channel Bandwidth or Channel Bonding First what this parameter is & then why some Apple devices do not like it, plus why within the 2.4GHz band, it can cause the speed to be worse than with it disabled. The ability to add a second channel was introduced with 802.11n, & enhanced with 802.11ac, to double (or more) the available Wi-Fi bandwidth. Older standards 802.11b, or g do not support this. For this to work, both the router (or Access Point) and the wireless network adapter in the connected device must support a minimum of 802.11n, as well as this additional facility. Traditional 802.11 channels are 20 MHz wide, actually being made up of four 5MHz channels. If you look at the frequencies used by say channel 6, it goes from the mid-point of channel 4 through to the mid-point of channel 8. This actually does not use four channels, but five channels, due to starting & ending in the mid-point of two channels. If you then use a second channel with the channel bandwidth of 40MHz, this now spans the frequency range of 9 channels! It can be used in both the 2.4 & 5GHz frequency bands, but it works best in the 5GHz band. This often can make throughput worse if used in the 2.4GHz band, because there is only space for three, non-overlapping channels (1, 6 & 11). There is only enough space for one bonded channel in that portion of the RF spectrum, thus the chances of co-channel interference is greatly increased. It is recommended therefore to consider disabling this within the 2.4GHz band. With 5GHz, there are over 20 non-overlapping channels, so you can have several bonded channels operating without a problem. Some routers (such as the Huawei HG633) support up to 8 channels bonded together. Once again the network adapter in the wireless device would have to support this number of channels for it to work. Depending on the make/model of router this can be called:1. 2. 3. 4..11n bandwidth Channel width Bandwidth Channel bonding Page 21 of 27

You may see your network card reporting a speed or bandwidth of 150 or 300Mbps in the connection status (see this example from Windows 7):- The settings for this (depending on make/model of router) is 20/40MHz or some combination of the two on Huawei routers. D-Link routers tend to have options such as "Up to 65Mbps", or "Up to 135Mbps" etc. Some routers now even offer 60Mhz as an option (3 channels). Taking the Huawei range of routers as an example, if using the option "20/40MHz" the router will negotiate with the network card when a wireless connection between the two is established. Both devices will use the highest supported common setting. So if the network card only supports a bandwidth of 150Mbs, the they will both only work at 150Mbps, even though the router can run at a higher bandwidth. If the network card supports 150, 300 and greater bandwidth settings, the highest common one is 300Mbps. Assuming the router is setup to use wireless channel 6, and the router & network card have negotiated to use 40MHz. This means that channel 6 can handle a bandwidth of 150Mbps, but that it requires an extra channel to use, if the amount of data flowing across your network card exceeds 150Mbps. That extra channel it can then use is channel 10. This allows up to a total of 300Mbps when using both channels. Depending how technical you are, why am I one moment talking Mbps and then in frequencies MHz? Each channel on an 802.11n uses a 20MHz frequency band. Some D-Link routers show the setting as "Channel Width" and give it in Mbps. This all sounds great, unless you use any Apple devices, as they don't particularly like the 20MHz/40MHz 802.11n bandwidth. This can cause these devices not to be able to find the WiFi network in question. Note: if this option is set to use only 1 channel, you will get slower speeds on these devices. To check this log into the router & follow as per the particular router. Most TalkTalk routers are covered over the next few pages. Page 22 of 27

Huawei HG633/HG635 Once logged in, go to:home Network > Wireless Settings Then expand the Advanced settings section. Go to the 2.4GHz Frequency Band section & change the.11n bandwidth option to 20MHz :- Page 23 of 27

Huawei HG523a, HG533 & some DSL-3780 routers Go into Advanced mode, then go to Basic > WLAN In there change the "11N band width" option from 20/40Mhz to just 20MHz & see how that goes. D-Link DSL routers & DSL-3780s Click the "Advanced" button from the initial summary screens & click on "Advanced" tab along the top, followed by "Advanced Wireless" on the left. Set the bandwidth based on what is required, if it uses one channel this is the equivalent of 20MHz & two channels uses 40MHz. On the 3780 the bandwidth option is in the "WLAN Performance" section, which is off "Advanced Wireless" down the left hand side:- Please see next page. Page 24 of 27

Here the bandwidth option is called "Channel Width", this is it set to use two channels (40MHz) Forces to 300Mbps :- Here is it set to use one channel (the equivalent of 20MHz) up to 270Mps :- Page 25 of 27

D-Link DSL-3782 Go to:settings > Wireless (Wi-Fi) In the 2.4GHz band select Advanced Settings In the performance section set the Channel Width to 20MHz:- Click the Save button. Then go to the 5GHz advanced settings & this can be found in the same area. This should be left at 20/40/80MHz normally:- Click the Save button again. More details on this setting:http://www.pcmag.com/article2/0,2817,2405996,00.asp Problems with ipads & some D-Link routers For some reason, ipads struggle to work with the D-Link DSL-2780. Page 26 of 27

Interference from other 2.4G non 802.11 devices Devices such as microwave ovens, Bluetooth, video senders, door bells, DECT cordless phones, speakers & sub-woofers (including those used with a PC), intruder alarms and wireless keyboards & mice all operate at 2.4GHz, but do not conform to the 802.11 specifications. Therefore you will not see them with a Wi-Fi analyser such as Acrylic. However, their background RF can interfere with the 2.4G band of 802.11, but you would probably need a spectrum analyser to see this. More information on these products:1. 2. 3. 4. 5. 6. 7. 8. 9. Microwave ovens Video Senders cordless (DECT) phones Bluetooth devices door bells intruder alarms wireless keyboards & mice Video Senders Car alarms/remote central locking General information on RF interference on 802.11 wi-fi networks. Page 27 of 27