Sometimes things are not what they seem to be on the surface. I was getting lousy PING times to 126.96.36.199 at home for weeks with Centurylink, my ISP. The problem was especially bad at night. I chalked it up to too much competition for their bandwidth for streaming Netflix and other on-demand media. Their customer support was useless. They only knew enough to walk you through power-cycling your DSL modem.
ISP # 2
Hitting a brick wall, I decided after all these years to switch ISPs to Service Electric Broadband Cable. My standalone test with their modem showed good throughput. Something like 29 mbps download and 3 mbps upload using speedtest.net. Then after a few days I got around to putting more of my home network on it and the service degraded as well. could it be that both ISPs were bad at the same time? PING times were between 200 – 900 msec, with plenty of timeouts in between.
I noticed that if I power-cycled the modem things ran pretty well for a minute or two, then started going downhill again. I had observed the same thing when they had me power cycle the DSL modem. Then I noticed that when I restarted my laptop the situation improved for awhile, then degraded. So it finally dawned on me that this one laptop was correlated with the problem. In Windows 10 Task Manager it has a convenient process view that allows you to view the top bandwidth-consuming applications (click on Network).
Suspicions raised around Google Drive
There I saw that Google Drive was consuming 3 mbps! Is that a lot or not? It all depends on whether it is downloading or uploading files. In my case I happened to put several multi-GByte movie files on my laptop on the Google Drive. So clearly it was trying to upload them to the cloud. Plus, worse, the power management was such that the laptop was only powered on for a few hours – not long enough for any of those files to finish uploading!!
The short-term solution
Google Drive has a feature that allows you to limit bandwidth usage. When I set that I wanted to keep the upload going but I also wanted to work. I settled on upload of about 240 KB/sec and download of 2000 KB/sec. I figured it was high enough to use most available bandwidth, but save some for others. And I changed my power management scheme to never hibernate when plugged in.
While the files were uploading performance of PING was still quite impacted, but I was doing VPN pretty comfortably so I left it alone. It was certainly better. When all files finished uploading after a few days my performance with the new ISP was great.
Why did rebooting the DSL modem help?
During reboot no Internet connection is available and Google Drive goes into an error state No connection. Periodically it checks if the Internet connection is working. Finally after a modem reboot it does begin to work, then eventually Google Drive will realize that. But even once it does, it starts from the beginning and scans all the files to see what needs to be sycned, and that takes awhile. So only after a few minutes does it begin to use your Internet bandwidth. Meanwhile you think everything is good, until it very quickly turns bad again!
A problem with an ISP at night is explained by the presence of an application that was taking all available bandwidth for doing massive file uploads which never completed! A change to a new ISP was not such a bad thing as it is faster and cheaper.