android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

kristapsd · Thu Jan 17, 2019 11:21 pm

Hi!
my two android devices always chooses 2.4Ghz over 5Ghz when same SSID is set for both frequencies.
Is this normal behavior of android devices?
how i tested it:
1. disable 2.4Ghz
2. both reconnects to 5Ghz
3. enable 2.4Ghz
4. after about 15 to 20 minutes both are back to 2.4Ghz

setup:
wlan1 - 2.4Ghz
wlan2 - 5Ghz
router - hAP ac^2 6.43.8 (stable)
00:0A:F5:XX:XX:XX - android 9.0, Xiaomi
80:58:F8:YY:YY:YY - android 8.1, Motorola

## disabled wlan1 - 2.4Ghz
21:42:37 wireless,info 00:0A:F5:XX:XX:XX@wlan1: disconnected, disabling 
21:42:37 wireless,info 80:58:F8:YY:YY:YY@wlan1: disconnected, disabling 
21:42:37 system,info device changed by admin 
21:42:45 wireless,info 00:0A:F5:XX:XX:XX@wlan2: connected, signal strength -51 
21:42:46 wireless,info 80:58:F8:YY:YY:YY@wlan2: connected, signal strength -45 
21:42:51 dhcp,info defconf deassigned 192.168.AA.DD from 00:0A:F5:XX:XX:XX 
21:42:51 dhcp,info defconf assigned 192.168.AA.DD to 00:0A:F5:XX:XX:XX 
## enabled wlan1 - 2.4Ghz
21:43:32 system,info device changed by admin 
21:44:18 system,info,account user admin logged out from 192.168.AA.BB via web 
21:44:52 wireless,info 00:0A:F5:XX:XX:XX@wlan1: connected, signal strength -28 
21:44:52 wireless,info 00:0A:F5:XX:XX:XX@wlan2: disconnected, registered to other interface 
21:44:55 wireless,info 00:0A:F5:XX:XX:XX@wlan1: disconnected, received deauth: sending station leaving (3) 
21:44:59 wireless,info 00:0A:F5:XX:XX:XX@wlan1: connected, signal strength -33 
21:45:04 dhcp,info defconf deassigned 192.168.AA.DD from 00:0A:F5:XX:XX:XX 
21:45:04 dhcp,info defconf assigned 192.168.AA.DD to 00:0A:F5:XX:XX:XX 
21:46:04 wireless,info 80:58:F8:YY:YY:YY@wlan1: connected, signal strength -41 
21:46:04 wireless,info 80:58:F8:YY:YY:YY@wlan2: disconnected, registered to other interface 
21:46:45 wireless,info 00:0A:F5:XX:XX:XX@wlan1: disconnected, received disassoc: unspecified (1) 
21:46:46 wireless,info 00:0A:F5:XX:XX:XX@wlan2: connected, signal strength -51 
21:47:04 wireless,info 00:0A:F5:XX:XX:XX@wlan1: connected, signal strength -27 
21:47:04 wireless,info 00:0A:F5:XX:XX:XX@wlan2: disconnected, registered to other interface 
#############
## Both are back to 2.4Ghz, below another try
#############
21:55:12 system,info,account user admin logged in from 192.168.AA.BB via web
21:56:26 wireless,info 00:0A:F5:XX:XX:XX@wlan1: disconnected, disabling 
21:56:26 wireless,info 80:58:F8:YY:YY:YY@wlan1: disconnected, disabling 
21:56:26 system,info device changed by admin 
21:56:31 wireless,info 80:58:F8:YY:YY:YY@wlan2: connected, signal strength -40 
21:56:35 dhcp,info defconf deassigned 192.168.AA.BB from 80:58:F8:YY:YY:YY 
21:56:35 dhcp,info defconf assigned 192.168.AA.BB to 80:58:F8:YY:YY:YY 
21:56:57 wireless,info 00:0A:F5:XX:XX:XX@wlan2: connected, signal strength -51 
21:56:57 dhcp,info defconf deassigned 192.168.AA.DD from 00:0A:F5:XX:XX:XX 
21:56:57 dhcp,info defconf assigned 192.168.AA.DD to 00:0A:F5:XX:XX:XX 
21:57:01 system,error,critical login failure for user admin from 192.168.AA.BB via web 
21:57:13 system,info,account user admin logged in from 192.168.AA.BB via web 
21:57:27 system,info,account user admin logged out from 192.168.AA.BB via web 
21:57:57 system,info device changed by admin 
22:15:45 wireless,info 00:0A:F5:XX:XX:XX@wlan1: connected, signal strength -47 
22:15:45 wireless,info 00:0A:F5:XX:XX:XX@wlan2: disconnected, registered to other interface 
22:15:48 wireless,info 00:0A:F5:XX:XX:XX@wlan1: disconnected, received deauth: sending station leaving (3) 
22:15:52 wireless,info 00:0A:F5:XX:XX:XX@wlan2: connected, signal strength -57 
22:15:52 dhcp,info defconf deassigned 192.168.AA.DD from 00:0A:F5:XX:XX:XX 
22:15:52 dhcp,info defconf assigned 192.168.AA.DD to 00:0A:F5:XX:XX:XX 
22:18:27 wireless,info 80:58:F8:YY:YY:YY@wlan1: connected, signal strength -30 
22:18:27 wireless,info 80:58:F8:YY:YY:YY@wlan2: disconnected, registered to other interface 
22:18:30 dhcp,info defconf deassigned 192.168.AA.BB from 80:58:F8:YY:YY:YY 
22:18:30 dhcp,info defconf assigned 192.168.AA.BB to 80:58:F8:YY:YY:YY 
22:18:47 wireless,info 00:0A:F5:XX:XX:XX@wlan1: connected, signal strength -51 
22:18:47 wireless,info 00:0A:F5:XX:XX:XX@wlan2: disconnected, registered to other interface

whatever · Fri Jan 18, 2019 9:08 am

You can raise the "antenna gain" setting on the 2.4GHz interface by some db, this will lower its tx power and cause most clients to prefer the now stronger 5GHz network.
However, this will also reduce your 2.4GHz signal range, so this "solution" isn't always feasible.

Fri Jan 18, 2019 1:15 pm

Since 2.4GHz better penetrates walls and goes around obstacles, it's possible it's signal is simply better.
Devices will prefer 5GHz only if the signal is good on both.

mkx · Fri Jan 18, 2019 2:00 pm

There are apps for android that, when installed on mobile, push device to 5GHz band even if signal strength is lower than on 2.4GHz. One example is Wifi 5. Worked for me nicely on an old Galaxy S4, which highly preferred 2.4GHz WiFi if left alone.

Pea · Fri Jan 18, 2019 4:58 pm

Other option would be to setup different SSID for 5GHz. And never connect phone to your 2.4GHz

r00t · Fri Jan 18, 2019 5:06 pm

Other vendors offer "band steering" that usually works well and can move devices that support 5GHz to that band, freeing 2.4GHz for devices that can't work anywhere else.
See viewtopic.php?f=7&t=127742 for more info and actual implementations used.
Sadly Mikrotik doesn't seems to be interested in such feature...

kristapsd · Sun Jan 20, 2019 12:12 pm

forgot to mention that this is one room condition - both phones, laptop and router are in one room max 3m away.
bringing phones into wifi range, they both initially connects to 5ghz and after some time they switches to 2.4Ghz and stays there.
next observation is that they drops to 2.4Ghz when 5ghz is not actively used at least on one of devices, for example, i tried to monitor wifi devices with winbox (laptop connected to 5ghz) or webfig from phone, while winbox or webfig is open, none of devices switches to 2.4Ghz. when laptop is shut down or phone is put to stand by, almost imediately both phones switches to 2.4Ghz and stays there. can not tell about laptop switching to 2.4Ghz because there is always some network activity on windows while turned on.
Is there any explanation why this is happening. for me it does not look like normal behavior.
hope you understand my problem and concerns

Kristaps

Jotne · Sun Jan 20, 2019 12:56 pm

There are apps for android that, when installed on mobile, push device to 5GHz band even if signal strength is lower than on 2.4GHz. One example is Wifi 5. Worked for me nicely on an old Galaxy S4, which highly preferred 2.4GHz WiFi if left alone.

Some comments about the Wifi 5 program.

1. It's not located at Google Play, so you need to trust an unknown source.
2. It tells me that my Android is to new and that it may not work.
3. It only work if you have same SSID for 2.4GHz and 5GHz. No option to tell it that you have two different SSID..

WeWiNet · Sun Jan 20, 2019 1:39 pm

Indeed no air time fairness or band steering nor even roaming in ROS, so you need to do it by yourself with basic method via access list:
Use 2 access list entries for forcing phone to 5G and if that signal is too low (=bad) , allow 2.4G access!
Set signal strength to access 5Ghz network to something like -70..120
to find what value exactly you want to use (here example is -70):
- Put your phone at the limit of the room, allow connection to 5Ghz and check signal strength. I find a value of -60
- to this value add another 10 to allow possible variations -> -70
- Now create a 2nd rule that allows access to 2.4G only and give it signal strength to access -120..-65. ( have them overlap by 5
roughly to make sure you can always connect).

note/comment before some will say this works really not too good (which I agree with, but is the only solution today in ROS)
- this works really really rough only, but it is enough for devices to make sure in one room close to the AP that 5G is used
- you will need to play with values
Ideally go further and further away while connected to 5G Wifi and see how good connection speed is. When connection gets unstable
use a value close to that.

Hope this can help a bit.

mkx · Sun Jan 20, 2019 1:42 pm

There are apps for android that, when installed on mobile, push device to 5GHz band even if signal strength is lower than on 2.4GHz. One example is Wifi 5. Worked for me nicely on an old Galaxy S4, which highly preferred 2.4GHz WiFi if left alone.
Some comments about the Wifi 5 program.

1. It's not located at Google Play, so you need to trust an unknown source.
2. It tells me that my Android is to new and that it may not work.
3. It only work if you have same SSID for 2.4GHz and 5GHz. No option to tell it that you have two different SSID..

1. Could be, I just used it as an example, there are many such apps still available on google play
3. No device will perform seamless roaming between different SSIDs as using different SSIDs implies different networks (even if they aren't). Either user has to select different network by hand or device will select different network automatically when current network is lost and will not return to the old network if new network is present. Hence suggestion by @Pea above.

Pea · Sun Jan 20, 2019 2:30 pm

forgot to mention that this is one room condition - both phones, laptop and router are in one room max 3m away.

Ideal situation. Why you even use 2.4GHz? Stay with 5GHz only and problem solved.

Petri · Mon Jan 21, 2019 12:14 am

If you set the 2.4GHz transmit power 6dB lower than 5GHz the the device will perceive them as equally strong. If you set it lower then the 5GHz will appear stronger and be chosen. Most devices will prefer 5GHz if the signals are equally strong. That's why 6dB difference usually does the trick. You can use the Antenna Gain field for adjusting as @whatever suggested.

The Free-Space Path Loss formula states that the signal attenuation is relative to the square of the frequency (or wavelength). 5GHz is roughly the double of 2.4GHz – double squared is four – quadruple is 6dB Δ

It doesn't matter if you are in the same room. With equal distance and receiver the signal strength difference will be 6dB.

However, I usually name the SSIDs differently, like Corporate and CorporateSlow. You can guess which one 2.4GHz!

Jotne · Mon Jan 21, 2019 8:46 am

However, I usually name the SSIDs differently, like Corporate and CorporateSlow. You can guess which one 2.4GHz!

I do that as well. It will then be up to the users if they like the one or the other.
If you never connect to 2.4GHz SSID, it will always take the 5GHz SSID if you have connected to it once.

mkx · Tue Jan 22, 2019 8:39 am

It doesn't matter if you are in the same room. With equal distance and receiver the signal strength difference will be 6dB.

Not entirely true, building materials generally attenuate higher frequencies much more than lower frequencies. So the rule of 6dB might be quite right for open space / single room, but it isn't true when there are physical obstacles between AP and client. (BTW, actual real-life path loss in mobile networks is proportional to exponent higher than 2, in certain terrain and land use configurations it might be as high as 3.5 ... while in certain situations, such as road/railway tunnels it might get as low as 1.2).

Another problem with lowering 2.4GHz Tx power is that then one could wonder why to use it then at all? All modern devices support WiFi on both bands so it might be quite feasible to just switch off 2.4GHz WiFi if that's not needed for extra coverage.
I still think that best solution when one wants to have seamless roaming between 2.4GHz and 5GHz APs is to somehow force devices to use 5GHz AP if signal is decent. Which can be either done as @WeWiNet suggested or by installing one of those "prefer 5G" apps.

android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

Re: android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

Re: android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

Re: android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

Re: android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

Re: android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

Re: android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

Re: android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

Re: android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

Re: android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

Re: android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

Re: android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

Re: android devices chooses 2.4Ghz over 5Ghz on hAP ac^2

Re: android devices chooses 2.4Ghz over 5Ghz on hAP ac^2