Suddenly WiFi signal strength is poor
#1
The WiFi signal strength has become very poor on my Pinephone. I suspect it is a hardware issue and I’m looking for some pointers on how to diagnose the problem.

Some data points using wavemon:

PinePhone (approx 6ft away): -86 dBm, quality 33%
PinePhone (approx 1ft away): -62 dBm, quality 70%
Laptop (approx 6ft away): -39 dBm, quality 100%


I understand that the antenna connects from the mainboard to the inner frame which has the antenna on it. I put pressure on that corner of the phone to see if it may not have made a good connection to the case but that doesn’t seem to change the signal strength. I’ve taken the inner frame off to try and reseat it but that didn’t show any improvement.


Is there a way I can narrow the problem down to the case, the mainboard, or the connection between them? Any tips?
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#2
I would disassemble to check for defects/loose antenna.

Increasing txpower:
Code:
sudo ifconfig wlan0 down && sudo iwconfig wlan0 txpower 30 && sudo ifconfig wlan0 up
- RTP

"In the beginner's mind there are many possibilities, in the expert's mind there are few." -Shunryu Suzuki


[ Pinephone Original | Pinetab v1 / v2 Enjoyer ]


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#3
Just for curiosity sake I would try another operating system from an sd card, before taking the phone apart.

You did say, it just started receiving wifi weakly, it was receiving better previously ?
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#4
I was running the latest Mobian with 5.10 Kernel. I tried a range of different software first (Postmarket Plasma, Postmarket Phosh, a few distros on the the multi-boot SD card). I tried upgrading to the 5.13 kernel on Mobian and that also didn't make a difference to the signal strength.

I've taken the phone apart a few times at this point trying to understand what could have broken. I am assuming the small shield on the upper right corner on the back of the mainboard is the RTL8723CS. (I didn't see any other place it could have been). That shield is right next to the antenna pins and the traces disappear in the PCB. If there is a problem with the mainboard it doesn't look like there's anything I could do about it. I don't think it can be a loose connection either if the case antenna just presses against the pins when you screw it down.

Running the phone without the back frame I get the same signal strength (so the antenna isn't being useful), but that doesn't really help me narrow down the problem. I tried effecting the signal strength by attaching other wireless antennas, pieces of wire, or just my finger. I didn't see much change, but I'm not sure that's a valid test.

I did try those commands to change the transmit power but I couldn't get by "Operating not Permitted". I couldn't tell if it was because the driver doesn't support that, or if it's my regulatory environment. Even passing it iwconfig wlan0 txpower off failed with that error.

At this point I don't know any other tactic then to buy a back frame and a mainboard and see which part fixes the problem.
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#5
I replaced the mainboard and the inner frame, and replacing the mainboard brought back a good WiFi signal. Replacing the inner frame didn't make a difference.
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