How to rule in or rule out notebook wireless hardware problems

This notebook computer was connected using Ethernet for many months.
Today attempts to connect wirelessly initially failed.

Parts of the troubleshooting included running the windows network troubleshooter, downloading drivers, rebooting, working with a google fiber technician, etc.

For internet there is a google network box with fiberjack.
In one room there is a range extender.

For wireless the notebook can detect 4 signals: 2.4 and 5 from the google network box, and 2.4 and 5 from the range extender.

Google fiber troubleshooting included turning off the range extender and resetting both the network box and fiberjack.
With all of the steps the wireless displayed a yellow triangle with black exclamation mark in the lower right corner.
The yellow triangle would disappear when selecting a different signal and then reappear when a google fiber speed test was performed.

A second notebook was then tested and it was able to connect to all 4 signals without problems.

The conversation was completed with the Google technician and I was surprised to see the first notebook connected wirelessly. It has been connected to the range extender at 2.4 GHz and is next to the second computer.

I'd like to run through troubleshooting steps to determine whether there is or is not a hardware problem.

What are the tests, routine, and rigorous, that could rule in or rule out a hardware problem?
The Windows version is 1809.

There are two computers that are the same model and one has a malfunctioning keyboard.
For this notebook I've been using the on screen keyboard.
The on screen keyboard is not available in windows RE after clicking startup settings > restart
Some of the regular keyboard keys do not work and the #5 key was not able to be clicked to launch safe mode with networking.
For the other notebook I've confirmed that safe mode with networking displays available wireless networks.

For the notebook that uses the on screen keyboard the #4 key worked and safe mode was opened.
It displayed: Looks like you aren't connected to the internet.
Try these things to troubleshoot network connection issues in Windows 10.

Settings > network and internet > wifi > show available networks
If those don't work then try the network troubleshooter.

Network and internet displayed:
status
dial up
vpn
data usage
proxy

There was no wifi option.
Clicking on status had an option to show available networks but this did not work.

The second notebook was then booted into safe mode and it displayed similar results using settings.
Show available networks did not work and displayed airplane mode.

The network troubleshooter does not work in safe mode.

Scannow and restorehealth were clean.

HP UEFI hardware diagnostics were on a flash drive.
The notebook was booted to the HP UEFI hardware diagnostics on the flash drive.
The test options included network: the test will attempt to configure the network controller using DHCP and communicate with the DHCP server (60 second test). This test passed.

The HP UEFI hardware diagnostics on the internal drive had a diagnostic test for wireless module.
This test will check your system to make sure the wireless module was properly detected by the BIOS and is enabled for use (30 second test). This test passed.


What else can be done to test wireless hardware?
For example, Acer or Sony notebooks that do not have bootable diagnostics?

The computer is having problems continuously remaining connected to wireless and at random times will display a yellow triangle with black exclamation mark in the right lower corner.
Running the network troubleshooter always displays the default gateway is not available > fixed
Reset the "Wifi" adapter completed.

I would consider using a WiFi analyzer, which can show you who is using what channels in your area, your signal strength, and your signal-to-noise ratio (SNR)...

For Windows users, I would recommend NetSurveyor, Acrylic WiFi, inSSIDer, and Wi-Fi Scanner (Lizard Systems).

Run it on the problem system, and try it in different areas of the house.

If the system is close to the WiFi router, you might consider using the 5 Ghz band, which is less crowded, but not good for devices farther away.

Use 2.4 Ghz for those devices, but that band is more crowded.

It's a balancing act.

On the router side -

If you are using auto channel select, try using channel 1, 6, or 11 for 2.4 Ghz, and 153 for 5 Ghz.

Wireless Security should be using WPA2-Personal with AES encryption.

Select NG-Mixed for 2.4 Ghz and AC/N-Mixed for 5 Ghz if it's available on your router.

WMM should be turned on for both bands, and try the Beacon Interval at 100 and RTS Threshold at 2346.

If you make any changes, reboot the router and re-test your wireless connections.

The signal strength can be removed from the troubleshooting as both notebooks are on the same desk.

The distance to the network box is approximately 25 feet and the distance to the range extender approximately 12 feet.

There is open air to the range extender and a closet dry wall for the network box.

I've got a wifi analyzer on my smart phone that was used approximately four years ago during the setup.
Not using it for years I've forgotten how to use it to reevaluate the four different signal strengths.

The problem is the unexpected wireless disconnects with the displayed yellow triangle.
How to test the hardware?

I would use one of the suggested WiFi analyzers on the system.

Try uninstalling the adapter and let Windows re-install it.

I would then go into the adapter Properties, and select Configure, Power Management, and turn off power saving settings.

If I'm not using IPv6, I disable that on the adapter.

I wouldn't rule out signal as an issue yet.

I would still walk around the house with an analyzer running on the system to see if it can hold a signal at all.

Sounds like you're connecting, but the signal may be too weak, or dropping frequently.

Both computers have different wireless NICs, and different wireless radios.

The other system could have a better radio.

So they are different.

I would also confirm that the encryption for the wireless network matches what the router is expecting (which should be WPA2-Personal with AES encryption).

I would check the Windows Event Logs, and the router logs, for clues.

All else failing, you can get a USB wireless NIC for a small amount and compare its performance to the onboard NIC.

I have one for 5 Ghz on one of our laptops, and it works very well.

The wifi analyzer displayed range extender 2.4 GHz signal (approximately -20).
The wifi analyzer displayed the network box: 2.4 GHz (approximately -45)
The wifi analyzer displayed range extender 5 GHz signal (approximately -30)
The wifi analyzer displayed the network box: 5 GHz (approximately -50)

What does it display in the room where that system lives?

That's the end point for the connection.

Those were the numbers from above the keypad on the problematic computer.
The same numbers were seen above the keypad of the normal notebook (same model).

-20 is good signal strength.

-30 is good for 5 Ghz.

What is the signal quality? (percentage)