Bizarre Wi-Fi connectivity issues The problem started a couple of weeks ago. I noticed that when I had Google Drive actively syncing the Finder would frequently "refresh"; if I paused the syncing, this stopped. Moreover, if I left it syncing/refreshing for too long, the Wi-Fi would stop working, or the computer wouldn't wake from sleep. I was running Lion for I thought these issues might go away if I just upgraded to Sierra.

I uninstalled Google Drive; made Safari, not Chrome my default browser; and proceeded to make a Time Machine backup before the upgrade. While the Finder "refresh" issue has stopped, the connectivity issues have only gotten worse.

Basically, any time my Desktop tries to send/receive a large amount of data, it quickly slows the Wi-Fi to a trickle, and eventually makes it stop altogether. This includes:


Transferring files via "File Sharing" from my Desktop to my Laptop.
Downloading the Sierra update from the App Store.
Trying to re-sync my 900GB of Google Drive files.


Let me explain the symptoms. At first the Wi-Fi is working fine, and I can see all the signals around me:



Then after a while the transfer will become incredibly slow, and suddenly the list of networks around me becomes almost empty:



What is most strange is that some webpages will continue to load, and Dropbox will still sync. If I use terminal to ping (say google.com) it is around this time that I start to lose data packets, usually around a 2% loss rate. When this has happened for an extended period of time, or if I turn the Wi-Fi connection off and then on again, the list of signals becomes completely empty:



Nothing I do will reestablish the connection. Nothing will load, and I cannot access the internet until I have rebooted the entire computer:



I managed to hobble along and get everything backed up, and even got Sierra installed. However the issue has still been plaguing my Google Drive. I even re-installed it, and made sure Chrome was updated. I'm not sure if this is an OS X or Chrome/Google issue, as it seems to have a lot of symptoms in common with other peoples' issues for both situations.

I really need to access my Google Drive. Please, any help you can offer is very appreciated.
Not much of an "answer", but I eventually tried connecting the machine directly to the modem via an ethernet cable, and turned the wireless off altogether.

This solved my connectivity issues immediately. Since I tried troubleshooting everything I could find online, I am left assuming it must have been a failing wireless card. Unfortunately the Hardware Test diagnostics do not run on my computer (this machine has lots of problems...) so I can't tell for sure without simply getting a new card installed.

If anyone else is ever experiencing the same symptoms I was, maybe this is also your problem.