steeley
Posts: 41
Joined: Fri Jun 22, 2012 3:00 pm

TP-link Wifi dongle (RTl8812au) not seeing all wifi networkss

Fri Jul 24, 2020 8:34 pm

I have a TP-link archer 600 T2u, using Engman driver for RTL8812au and it does not see all the available wifi networks that are available in my home..

There are 2 networks it will not find even though it finds my 5ghz network and a host of other Sky boxes and neighbours BT wifi modems etc.
These networks show up and work ok when scanned from a Mac or Windows laptop.

I'm on pi3 Buster, kernel 5.4.51-v7+.

I've tried both these commands:
nmcli dev wifi list
iwlist wlan0 scan | grep ESSID

with and without sudo - doesn't seem to make a difference.

I can also use NetworkManager command line to make a hotspot wi the Tp-Link, and I can also manually use nmcli to connect to
the networks that don't show up in the scan!

I can also use the command line Horst wifi scanner, which does show the wifi networks which don't show up using iwlist or nmcli.

so.... what is happening any idea?? Maybe iwlist/nmcli is scanning too fast or something and missing data?

thanks.

User avatar
mooblie
Posts: 220
Joined: Fri Oct 14, 2016 2:07 pm
Location: The Scottish Highlands

Re: TP-link Wifi dongle (RTl8812au) not seeing all wifi networkss

Fri Jul 24, 2020 8:42 pm

Do you have, say, a Windows10 PC you could plug your adapter into, to find out what networks THAT sees?

It would help determine if the problem is your networks, the adapter, the Pi, PiOS, etc...etc...

steeley
Posts: 41
Joined: Fri Jun 22, 2012 3:00 pm

Re: TP-link Wifi dongle (RTl8812au) not seeing all wifi networkss

Mon Jul 27, 2020 8:53 pm

Thanks - I have a nasty feeling its something to do with the 8812au driver....

I borrowed some other dual-band dongles and if I try those they work ok - they use the RT3572 chipset.

I used the MrEngman script to get the TP-Link (8812au) working.

I seem to be up to date with the OS:
Operating System: Raspbian GNU/Linux 10 (buster)
Kernel: Linux 5.4.51-v7+

So my conclusion is the driver is currently broken for 8812au :(

MrEngman
Posts: 4076
Joined: Fri Feb 03, 2012 2:17 pm
Location: Southampton, UK

Re: TP-link Wifi dongle (RTl8812au) not seeing all wifi networkss

Mon Jul 27, 2020 9:33 pm

To get an up to date scan list you should use command

Code: Select all

sudo iwlist wlan0 scan
using sudo.

I'm not sure where iwlist .. scan gets it's info from but unless you use sudo iwlist ... it appears to get the scan data from stored data. Using sudo iwlist ... it appears to do a totally new scan.

Just tried a test on one of my PI and command iwlist wlan0 scan showed a single AP wth no delay. Running the command sudo iwlist wlan0 scan it takes some time to return the data, which would appear to show it is taking time doing a totally new scan, and it comes back with a list of between 5-7 APs using 2.4GHz and 5GHz networks.

Running command iwlist wlan0 scan again showed only a single AP.


MrEngman
Simplicity is a prerequisite for reliability. Edsger W. Dijkstra

Please post ALL technical questions on the forum. Please Do Not send private messages.

steeley
Posts: 41
Joined: Fri Jun 22, 2012 3:00 pm

Re: TP-link Wifi dongle (RTl8812au) not seeing all wifi networkss

Mon Jul 27, 2020 9:50 pm

Thanks for the info - I'm aware of the difference between using and not using sudo with iwlist scan. been caught out with that before!
I can confirm that it gives an updated as opposed to a cached(?) scan when using sudo iwlist scan wlan0.

The problem seems to be that it misses certain access points that are there all the time as confirmed by
using other dongles in the Pi
OR
scanning from a MacBook running OSX.

ganzgustav22
Posts: 115
Joined: Tue Feb 11, 2020 1:04 pm

Re: TP-link Wifi dongle (RTl8812au) not seeing all wifi networkss

Tue Jul 28, 2020 9:13 am

They could be on channels that are not allowed with the current regulatory domain settings.

Check with:

Code: Select all

iw reg get
To see which frequencies/channels are allowed. Then compare that with the channels the access points you cannot connect are using.

Edit: Also check with:

Code: Select all

iw list
To see channels/frequencies that might be disabled.

steeley
Posts: 41
Joined: Fri Jun 22, 2012 3:00 pm

Re: TP-link Wifi dongle (RTl8812au) not seeing all wifi networkss

Tue Jul 28, 2020 11:05 am

Thanks - don't see any channels missing with those iw commands. Tried many things , and have spent several days trying to fix.

Looking around the other Internet forums seem to indicate 8812au goes through various stages of working /not working correctly.

casperm123
Posts: 1
Joined: Tue Jul 28, 2020 12:10 pm
Contact: Website

Re: TP-link Wifi dongle (RTl8812au) not seeing all wifi networkss

Tue Jul 28, 2020 12:18 pm

Not sure if this is the same issue, but i'm having issues connecting to my WiFi Booster or extender(whatever its called).

I can see my main router fine, but any of my access points/boosters won't pick up.

I can tell because the signal is terrible even though im right next to the extender, tried the solutions proposed but still nothing...

Called my provider aswell but they don't have time until 14 days from now... guess i'll have to wait and keep trying solutions proposed here.

steeley
Posts: 41
Joined: Fri Jun 22, 2012 3:00 pm

Re: TP-link Wifi dongle (RTl8812au) not seeing all wifi networkss

Tue Jul 28, 2020 1:36 pm

I have now tried 2 different RTl8812 dongles and both show the same issue.

I also tried an RTL8811 dongle and that had the same problem.

I have borrowed 2 dual-band dongles that use the RT3572 and RT5572 chips and these work correctly. These are an older chipset I guess, so not so easy to find. Also I need to have a dongle that can be an access point.

So RTL88xx whatever is a broken waste of time.

raspmod
Posts: 28
Joined: Sun Nov 25, 2018 3:48 am

Re: TP-link Wifi dongle (RTl8812au) not seeing all wifi networkss

Wed Jul 29, 2020 1:54 am

I came here after searching on another thread I will post about. Just sharing some info here re: RTL8812AU.

Literally today I got this:
https://www.amazon.com/gp/product/B07FC ... UTF8&psc=1
"BrosTrend 1200Mbps Linux USB WiFi Adapter .. 2.4GHz, 2 X 5dBi Antennas, USB 3.0"

It's chipset is Realtek RTL8812AU. It works on the pi 4 - actually following the included instructions and ultimately loads a 88x2bu driver:

root@raspberrypiforme:~# lsmod | grep -iE 88x2bu
88x2bu 2342912 0
cfg80211 679936 2 brcmfmac,88x2bu

I get about -53 dbm from about 45 feet away but the pi is behind a closed door most of the time.
That's a step up from the -62 dbm i was getting from the onboard wlan adapter.

I tested w/no case because the aluminum whilst keeping the pi cool really hampered the wifi.
I was using wifi man on my Android.

I am running hostapd and raspap-webgui.
HTH

steeley
Posts: 41
Joined: Fri Jun 22, 2012 3:00 pm

Re: TP-link Wifi dongle (RTl8812au) not seeing all wifi networkss

Wed Jul 29, 2020 8:01 am

Thanks - interesting that it uses a seemingly different driver.

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