I also have a dual-band modem and my Del tablet see the 5Ghz side just fine running Windows 10.  What is the modem model that you are trying to connect to the WIFI modem with?

I also think that 5Ghz is not faster than the 2.4 Ghz, but just a band that has little traffic on it if you are in an environment where a lot of people are connecting to the 2.4 Ghz band because their WIFI devices are not able to connect to 5Ghz.

I use 5mhz A band.  Think all the win10 builds seem to save checking for 5mhz connections until it discovers all the 2.4mhz first and checks them out.  At least on my laptop that seems to be the norm.

   But it does work though, many times the 5mhz access point is slow to show up in the list of available connections.  

The 2.5mhz connection shows instantly every time. Then my immediate neighbors appear,  and then some more neighbors connections ... often about eight 2.5mhz connections will show so its a busy place here.  But its connections &  speeds are the same as the 5mhz.  

I turn the power down to minimum on the laptops intel wifi card, think its 1 milliwatt output.  High is 32 mw.  Works fine and identical on both 2.5 & 5mhz 150mbit single channel or 300 dual - always full speed internet.    

2.4 will have stronger signal at greater distances and 5mhz doesn't penetrate walls or other stuff very well.  

Unless the wireless adapter in the computer or laptop is dual band, it will not see the 5 GHz signal at all.  Many older and not that old devices do not have dual band adapters, though Apple has been pretty good about this. You need to check the specs of each device to make sure it either supports the ABGN or AC wireless standards.  Even if the adapter supports them, the 5 GHz signal drops off much faster than the 2.4 GHz, so the adapter is likely to see the 2.4 GHz signal is stronger and choose to use that band.  Also, in Windows Device Manager, Device Properties, Advanced Tab, many dual band adapters offer settings which can control which bands the adapter will use, and whether to prefer to use 5 GHz if it is available.

Many of us have been using dual band wireless adapters with dual band wireless routers successfully at 5 GHz throughout the preview.

I am presuming you have given the 2.4 GHz and 5 GHz bands different SSIDs on the wireless router. It's OK to give them the same name, but that makes it difficult to tell whether both bands are visible and which band a given device is using.  

 

my laptop and desktop is 2014 not old. I looked at the specs it is supposed to work. there is no reason for it at all. my Lenovo desktop is a gaming pc and laptop to.  and a lot of people are having a issue. Now since the new build to 10166 I think that is the build number from last week just updated, but now no wifi is working at all. I have a adapter I plug in my laptop to get the 5ghz but I should not have to use that at all. other then that I like windows 10 way better then any of the Microsoft windows so far, like that there is no freezing or delays.. I have windows 8.1 but went ahead and tried out the preview. I am hoping this will be fixed in the windows, I was able to use 5ghz on both computer and laptop in windows 8 however after the update to windows 8.1 and now 10 it stopped working. so I know for a fact my computers are eligible, my wifi modem is 802.11 abgyn and my computer is the same 802.11 abgyn and dual band compatible. 2.4 ghz is not fast at all either, I have 150 mbps download and only get between dial up speeds and 10 mbps, but when connected to 5 ghz I get 150 mbps download speeds. so yes the 2.4 ghz cant handle the speeds at all it is the worst. and my modem is a Motorola newest one 2015 edition which is a arris arris own Motorola now for modems or Motorola owns arris, I am not sure which lol. but I go have net gear and same thing. a lot of people are having issues just got it look it up. even in the feed backs people are complaining. so I think if your running a tablet then that is different then running a pc. Secondly a lot of the complaints are saying they had windows 7 and 5ghz was working then when updated it stopped so it is not a compatible issue it is software driver issues that needs to be looked into and fixed. what drivers are you guys using ? maybe this way it will help me troubleshoot it?

can you give me a website that walks me through how to do that? thanks

2.4 ghz is not fast at all either, I have 150 mbps download and only get between dial up speeds and 10 mbps, but when connected to 5 ghz I get 150 mbps download speeds. so yes the 2.4 ghz cant handle the speeds at all it is the worst. and my modem is a Motorola newest one 2015 edition which is a arris arris own Motorola now for modems or Motorola owns arris, I am not sure which lol. but I go have net gear and same thing. a lot of people are having issues just got it look it up. even in the feed backs people are complaining. so I think if your running a tablet then that is different then running a pc. Secondly a lot of the complaints are saying they had windows 7 and 5ghz was working then when updated it stopped so it is not a compatible issue it is software driver issues that needs to be looked into and fixed. what drivers are you guys using ? maybe this way it will help me troubleshoot it?

sorry I had one reply for all then did not know that it was replying to one person so I had to split my message up that I wrote earlier. Thanks everyone.

Could you please go to the Network and Sharing Center and click on Change Adapter Settings in the left column.  Let us know whether you see one or two wireless adapters listed.  For each, right click on it and then click on Properties.  Then click on Configure to display the adapter properties.  Have a look at the General, Advanced, and Driver tabs to see if you see anything interesting, especially any Advanced settings related to band.  If possible, post a legible screen shot of the Driver tab.  Otherwise, from that tab, give us the adapter name, Driver Provider, Driver Date, and Driver Version.

Go to the Xirrus web site then Resources and then Free Tools.  Download and install Wi-Fi Inspector (unless you already have an equivalent tool).  Run it, and if possible post a legible screen shot of its Network display.  Otherwise, see if it shows any 5G networks and what the signal is for that network, and the signal for your 2.4G network.  Run some of the Tests from the Test box and let us know the results. 

I should probably add that there are a lot of things that can contribute to problems accessing the 5G band, most of which are unrelated to the OS you are using.  It's the kind of thing where Google searches can be unhelpful, because too many people have the problem for too many different reasons, and they're all mixed up together.  They can be related to a noisy, and frequently used, microwave oven, wireless land line phones, or large mirrors between the device and the modem.

We will try to help you troubleshoot, but one thing that will help us is if you provide more detail about your specific situation.

You say you have a desktop and a laptop.  Are they both used in the same room?  How far apart are they?  Are they in the same room as the wireless modem?  Are there any differences in their wireless performance?  Are there other wireless routers nearby - in other units of the same building (house or apartment)?

Apparently the laptop has a built-in adapter and you also use a plug-in.  What is the model of the plug-in?  Is the network performance on the laptop the same when the plug-in is inserted and when it is removed?   Do you disable the built-in adapter when you are using the plug-in?

I asked some questions about the driver, settings, and running Xirrus WiFi analyzer in my previous post.  When you can reply to that, make sure it's clear which adapter you are reporting on.  You don't have to test all, but you should test one (desktop, in-built laptop, or build-in laptop) completely.

Thanks and good luck.

I am having the same problem. I believe this is a driver issue. I have two computers and both have windows 10. One has a netgeat usb n900 adapter the other a built in wifi adapter (I think Broadcom) my netgear starting have this problem with build 10166, my other computer no problem at all.

I am in the middle of trying to find a fix for this, also checking my other adapters to see if same. I will let you know if I get anywhere. I also ordered an new Linksys 1200ac adapter (hoping I don't have to wait for that one to fix or that has same problem)..:)