[PROBLEM] Losing Wifi Connection

[TamedShrew]

@TamedShrew

Your last remark "Nor has removing it from the case entirely" suggests the problem may not lie entirely in signal strength, but there are a few measures of the quality of the connection which can help.

From the command line of the player, you can run the following command

Code:

iwconfig

#or if you're sure that wlan0 is the WiFi interface

iwconfig wlan0

For example, here is the output from one of my players

Code:

pi@CM4:~ $ iwconfig
eth0      no wireless extensions.

wlan0     IEEE 802.11  ESSID:"Krypton"  
         Mode:Managed  Frequency:5.22 GHz  Access Point: A8:70:5D:49:74:BA  
         Bit Rate=433.3 Mb/s   Tx-Power=31 dBm  
         Retry short limit:7   RTS thr:off   Fragment thr:off
         Power Management:on
         Link Quality=66/70  Signal level=-44 dBm  
         Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
         Tx excessive retries:15  Invalid misc:0   Missed beacon:0

lo        no wireless extensions.

The link quality and signal level numbers are the first to look at. 

A lower link quality fraction suggests poorer performance.

Similarly, a lower signal level suggests the likelihood of poorer performance. Note that dBm (decibel-milliwatt) numbers run from 0 to -100 with 0 the highest and -100 essentially nonexistent. Tthis is a logarithmic scale so a change of 10dBm represents a factor of 10 change in power.

A typical rule of thumb I grabbed from somebody's blog is:

• -30 to -50dBm  – Excellent signal strength (Next to Router)
  
• -50 to -67dBM  – At Good signal strength for Web browsing, voice/video calls.
  
• -67 to -70dBM  – Best effort for Web browsing for reliable packet delivery.
  
• -70 to -80dbm  – Experience bad connectivity, Packet delivery may be unreliable.
  
• -90 to 100dBm – Worst signal strength.
  

And, yes, my example player is just across the room from my access point.

High numbers of retries and "invalids" also suggest poor performance.

Apart from signal strength, there's the question of radio frequency interference. The presence of multiple WiFi  sources can be a problem; so is using the 2.4GHz band because so many WiFi devices use it, because it's shared with Bluetooth devices, and because it's so close to the ISM band---think microwave ranges, for example.

Regards,
Kent

Footnotes:

• There are other Linux tools available which can slice and dice the data in more detail but I find this use of iwconf to be adequate for quick checks.
  
• It's common to see some variation in the signal strength measures for different WiFi adapters in the same equipment and location, but they generally agree. You'd think vendors would have this sorted in their firmware. Think again.
  

Thanks Kent @TheOldPresbyope very educational! I've done some tests and things aren't as good as I initially thought. Most of the time it's at -60dBM, but every so often it nose dives to -70dBM. I'd assumed that because we seem to stream films and our son plays online games without any hiccoughs it was good but there must be a lot of buffering going on.
I'm going to connect them all up with ethernet (as the player that I've temporarily wired in has no problems). Just got to convince my partner that it's ok to take up some floor boards!
Cheers,
Nick