The Problem:
WiFi signal from Google Fiber hardware is interfering with my preferred home WiFi hardware signal. I discovered that we cannot permanently disable WiFi on GFBR set-top box (STB) using Fiber software. It can be temporarily disabled using Fiber App, but it will eventually be re-enabled. I've tried using a crude "Faraday Cage" place around the STB, but this did not reduce the Fiber WiFi signal by more than ~5 dBm.
The Fix:
ATTENTION: If you want/need support from Google, or if you don't really know what you are doing... don't do this! Think of this as a warranty-voiding activity for the tech-savvy folks only.
You've been warned. To proceed:
1) Unscrew four (4) T9x40 screws found on bottom of GFBR set-top box.
2) Remove cover. See the white and black wires? Those six (6) wires (3 black + 3 white) are the WiFi Antennae. The top plastic plate is hinged. It gently lifts from left side to reveal 6 RF connectors.
3) Gently unplug the 6 RF connectors.
4) Once disconnected, pull the wires and RF connectors away from the
main printed circuit board (PCB). I recommend taping these to the underside of the
hinged platform to prevent an accidental short on exposed components
below. Be careful not to interfere with the fan/blower. Be careful not to apply tape to any metal surface. (Those metal-encased RF modules get hot-enough without additional insulation.)
5) Close the hinged platform back into place, reassemble the plastic enclosure and reinstall screws.
The Results:
WiFi Signal Strength Comparison
Before: -45 dBm After: -71 dBm Delta: -26 dBm
NOTES:
[1] Signal Strength measured using a smartphone app: WiFiAnalyzer (open-source) downloaded from Google Apps Store... this is not an Ad or endorsement. Just FYI. Your results may vary.
[2] Measurements taken less than 10 ft from Google Fiber / GFBR set-top-box (STB).
[3] Without turning off the RF modules, it is pretty much impossible to have no RF signal. But >25 dBm signal attenuation is plenty to ensure my preferred home WiFi hardware does not experience more signal interference form the Fiber hardware than it does from a neighbor's WiFi signal.