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My FP3 doesn't like higher 5Ghz Wifi channels, especially channel 116

Hi everyone,

when I wanted to transfer a larger file from my NAS to my FP3 I was surprised by the low speed.
I then found out that it was only connected to my 2,4Ghz Wifi, not the faster 5Ghz one (my FRITZ!Box 7560 router is providing both frequencies, with the same SSID).
Normally the phone should auto-select the better one.
Anyway, after forcing the FP3 to 5Ghz only, I was even more surprised (in a very negative way) that the phone could barely keep the connection stable. Speed was abysmal and the connection was lost every few seconds.

To make a long story short, after playing around with different 5 Ghz Wifi channels (disabling auto-channel selection in the router), it turns out that my FP3 has severe speed problems with anything higher than channel 112 (>5,560 Mhz), channel 116 (5,580 Mhz) being the worst with an instable connection.
I am now using channel 52 and the phone can reach 200 MBit or even higher.

I know that Wifi speed is tricky and depends on whether or not you have many other neighbouring Wifis but I wouldn’t say I am in overcrowded 5Ghz Wifi environment (only counting ~3 foreign 5Ghz Wifis with somewhat stronger signal).
My router actually auto-selected channel 116-128 because it was/is the least used range.

Can anyone confirm this?

PS: My girlfriend owns a FP2 and she has had a bad Wifi experience for a long time. This also seems to have improved after I have switched to channel 52!

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I had that problem with a Fritz!Box 6490 Cable, solution for me was to change the WiFi standard setting from “802.11n+ac” to “802.11n+a”.
No problem for me since then.

I might try that as well but since ac is (in theory) the more advanced standard, I’ll probably stay on ac.

Btw, we also have a Thinkpad P51 notebook and an Acer Switch 7 convertible and none of those have or had a problem with higher channels. Same goes for my old Sony Z3c.

Maybe this is related? My FP3’s wifi country code is set to US:

adb shell getprop ro.boot.wificountrycode
US

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As 5 GHz has a short range, you should be able to set it static in your WAP without it causing interference. This depends a bit on your environment, e.g. in a flat you might have some more interference but in general there are going to be like 2 neighbors and you just pick a frequency around it.

Go for a 40 MHz wide range, so that DFS works well.

US has nothing to do with this. In fact, US is very lenient on 5 GHz usage (as is EU and CH). See e.g.

Yeah, there’s your problem. In your WAP you need to enable the preference that it should prefer 5 GHz (“bandwidth steering”), or you put it on a different SSID and prefer the 5 GHz one manually (hence the 2.4GHz one is used as backup).

PS: if you’re transfering large files from your NAS you could consider plugging the FP3 in USB on the NAS.

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I don’t think that this is/was “the” problem. All other devices had no problem selecting the 5Ghz Wifi, even on channel 116. I guess the FP3 chose to connect to the 2,4Ghz Wifi because it couldn’t get a stable connection to the 5Ghz Wifi (but now on channel 52 it prefers the 5Ghz Wifi).
My AVM router doesn’t explicitly call it “band steering” but there is an option with a lengthy description that matches what “band steering” is doing, and it is activated!

Sure, there are always other ways. Way less comfortable, though.

Minimum RSSI set?

I just verified with UniFi AP-AC-Pro that Channel 116 (DFS) with a Channel Width of VHT80 works perfectly fine with FP3 and other devices.

There is no option for that.

Thanks for checking! So either it is specifically my FP3 or there is some incompatibility with the FRITZ!Box router.

Since I haven’t had any issue on channel 52, I am gonna live with that for now.

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I could try with less Channel Width. That might enforce it to go on Channel 116 only. Or you could check what your Channel Width is.

For now, it appears to be the combination of certain FRITZ!Box plus FP3.

(I can test 2 FRITZ!Box, but it will be in end of December 2019.)

FP3 with FRITZ!Box 7590 user here - similar (same) behaviour - Wifi connection very flaky with phone switching between 2.4GHz and 5GHz and ending up at 2.4
Fritz selected the higher channels (116 and up) as it would’ve been alone there. Else there are 10 (including mine) 5GHz networks now sharing the lower ranges.

After pinning the channel to 56 phone and box are good to go.

re:Channelwidth - 160MHz width is NOT allowed

@moldowan: you’re not alone :slight_smile:; thanks for starting this thread. I’ll try to investigate further later this evening.

Regards, Daniel

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Nobody suggested a channel width of 160 MHz. You could try between 20/40/80 though. What I’ll try is see if I can put it on 20 or 40 with channel 116. You could play around with it.

Also, the fact that you can see other networks on channels does not mean they’re having a good signal (you should check their RSSI). If their signal is weak, you won’t have much (if any) interference with them.

Sadly the FRITZ!Box doesn’t allow me to change the channel width. Only change was the mentioned 160MHz. This setting is not on though.


From the documentation

Allow wireless channels with 160-MHz channel bandwidth (5-GHz frequency band)

Increases the maximum radio channel width from 80 MHz to 160 MHz and allows the latest Wireless AC devices with 2 x 2 antenna technology to double their throughput rates.

Thanks for confirming!

The Fritz router seems to automatically use 80 Mhz channel width because it always shows a (max) channel usage of 4 (when 116 is selected: 116, 120, 124, 128, or when 52 is selected: 52, 56, 60, 64).
Each of those channels is 20 Mhz wide.

Could you try other frequencies as well, to check which ones exactly don’t work?

(Becomes understandable with DeepL.)

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Got this reply from support after I mentioned this thread:

We are already working on the wifi connection issue, it looks like it is a bug.

So we’ll have to wait and see…

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I was exited to see this change in the new firmware FP3 A.0110:

WiFi comaptibility improval

but it did not really change anything for me.
Channel 116 is still extremely unstable and 120+ is very slow.

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I can confirm the 5Ghz channel problem on the FP3 with the Fritzbox 7590. When using auto channel, the phone would not even connect to the network at all. Switching to channel 52 made it work properly in n+ac mode.

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Hi there,
i have been following this discussion since i received my FP 3 in December.
I always had connection issues with my FP3 at home (Fritz.box 6490 Cable @ 5Ghz and a Fritz.Repeater 310). However, i have no issues at work (Eduroam @ 5 Ghz - no clue what specific hardware that is).
My FP 3 does only connect to the Repeater (only supporting 2.4 Ghz) but never to the router itself. disregarding of my distance to the repeater, even when i´m in close proximity to the router.

I tried to change the router settings as described in this threat and a similar one - however no change what so ever - i hoped for the update not change either.

i guess this issue is really related to the WiFi-chip in the FP 3 and the fritz.box as all other devices get along pretty neatly with the 5Ghz network and switching between access points.

Meaning … if you would limit the phone to the 2.4 GHz band the connection would be stable?

Settings - Network & Internet - Wi-Fi - Wi-Fi preferences - Advanced - Wi-Fi frequency band

After initial problems I have a stable 5 GHz connection to my 6490 Cable for some time now, so something must be amiss here.

Fritz!OS: 07.12
5 GHz channel: fixed to channel 36
5 GHz WiFi standard: 802.11n+ac

802.11n+ac was a problem for me at first, you can set that to 802.11n+a for testing.
Some update on the phone fixed 802.11n+ac for me, though.

Fairphone OS version: A.0110 (January 5 security patch level)

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