Inspiron Chromebook 7486 Wi-Fi speed is very slow after recent Chrome OS update and firmware update

 

My Dell Inspiron Chromebook 7486 was working perfectly until about two weeks ago, then there was a Chrome OS update for the Stable Channel on September 8, 2021, followed by a firmware update a day or two later. Ever since then, my Wi-Fi speed has been extremely slow. I suspect one of these updates must have caused the problem.

I have tested three other devices on my network, including a Windows PC, Android phone, and an iPad, all of which are getting 14 Mbps download speeds, while my Chromebook is averaging 1.2 Mbps. The Android phone is about 6 feet farther from the router than my Chromebook, but it's still 10 times faster.

 

Here are some of the steps I've taken to try and identify the problem:

 

1) I checked to make sure my Chromebook is up to date. It's running Chrome OS version 93.0.4577.95, the latest version on the Stable Channel.

2) I rebooted my modem/router and Chromebook. That did not solve the problem. And I always shut down my Chromebook via the power button in the menu that appears when you click on the clock. I never close the lid when the computer is on, so it's definitely a complete reboot.

3) I ran the Chrome Connections Diagnostics extension multiple times in the past 30 minutes. It found no problems and had no failed tests, unlike this morning when it detected failed tests on separate occasions (though the Internet was exceptionally slow this morning).

 

I just wanted to emphasize a few things:

1) The Chromebook was working perfectly until the Stable Channel update on September 8 and the firmware update released a day or two later.

2) The Chromebook is able to connect to Wi-Fi just fine, so speed is the only real problem.

3) I ran the Chromebook in Guest Mode to see if it might be an extension or Android app causing the issue, but performance remains the same regardless of whether I'm signed in to Guest Mode or a Google Account.

4) Earlier today, the Chromebook was running at 14 Mbps for about 10 minutes while signed in to Guest Mode, and it remained that high while using a Google Account immediately afterward, but after I shut down the computer and turned it back on again, the speed returned to 1.2 Mbps and stayed there while using Guest Mode and while using my Google Account immediately afterward.

 

Just a little more information:

I ran the Measurement Lab speed test about 15 times while writing this post, and the speed varied wildly:

It hovered between 1.2 and 2.5 Mbps for a few tests.
It averaged 4.5 Mbps for a few tests.
Iit averaged 13.7 Mbps during one test.
It averaged 6.3 Mbps for one test
It averaged 0 Mbps for 2 tests (it failed to start).
It averaged 1.8 Mbps.

Seeing as how it averaged 13.7 Mbps on one test, I'm wondering what on earth the problem could be, especially since the speed is consistently 14 Mbps for all of my other devices. My Internet plan maxes out at 15 Mbps, so 14 Mbps is pretty much the best I can hope for when it comes to Wi-Fi.

I posted most of this content in a thread on the Google support forums with an almost identical subject line and a lot of the same content, and so far no one has been able to find a solution there. I have updated Chrome OS twice since the problem occurred and none of those updates resolved it. I suspect the firmware update around September 9 or 10 might have caused the problem. If anyone knows what that firmware update was for, I'd be curious to know.

I'm hoping someone here can help me since the Inspiron Chromebook 7486 is a Dell product. Thanks in advance.