Weak and highly position-sensitive Wi-Fi signal on StackChan #119

Summary

StackChan shows substantially weaker and more position-sensitive 2.4 GHz
Wi-Fi than a mobile phone in the same small desk area.

Moving it only a short distance between nearby positions on the desk can
change its displayed signal from approximately 0/4 bars to 3/4 bars. We have
not established that orientation is the determining factor.

This is separate from #110, which concerns selection of a weak BSSID when
several APs advertise one SSID. The symptom here should be measured while the
device remains on the same BSSID.

Observed behavior

• StackChan reports much weaker Wi-Fi than a phone in the same desk area.
• A small position change can produce a large displayed-signal change.
• The weak link can coincide with unstable network behavior.
• Raw same-BSSID measurements have not yet been collected, so this report
  does not claim a specific root cause.

Relevant firmware behavior

The firmware derives the icon directly from the associated AP's RSSI:

• RSSI >= -65 dBm: high
• RSSI >= -75 dBm: medium
• RSSI < -75 dBm: low

There is no averaging or hysteresis, so a single sample crossing a threshold
changes the icon abruptly. This can exaggerate displayed instability, though
it does not explain persistently weak raw RSSI.

The firmware also uses WIFI_PS_MAX_MODEM with a listen interval of 10 while
idle. Power saving can affect latency and connection reliability, but should
be evaluated independently from received RSSI.

Suggested software investigation

1. Log raw RSSI, BSSID, channel, disconnect reason, and current power-save
   mode so tests compare the same AP rather than bar icons.
2. At one fixed position and BSSID, compare WIFI_PS_MAX_MODEM,
   WIFI_PS_MIN_MODEM, and WIFI_PS_NONE for reconnects and latency.
3. If raw RSSI is stable but the icon fluctuates, add short smoothing and
   threshold hysteresis to the display only.
4. Treat the strongest-BSSID selection fix in WiFi provisioning associates but never obtains an IP on mesh networks (scan_method left at WIFI_FAST_SCAN) #110 as a separate change.

Could M5Stack reproduce the same-position signal variation and share raw RSSI
measurements from the associated BSSID?