Last year I had a very weird issue that every few hours I would get huge pings(1700ms+) and my 15mbps connection would to like < than 1 mbps download and like 0.25 Upload. All devices on my network would be effected.
After talking to my ISP provider many times nothing seemed to work, they finally sent me a new router and I formatted my computer to Windows 8.1
The issue seemed to be resolved and no problems. I think I finally know what the issue was. I have a personal blog on a very cheap hosting.
Because of this I would create a backup of my site and use a program call allwaysync to sync that backup to my home computer and then upload it right away to Google Drive.
This way I had 3 backups(1 on the hosting server, 1 on my local drive and 1 in the cloud).
Now it seems the fact of uploading kills my network. I did some tests and when I uploaded a file to Google Drive as soon as I started to upload my ping went from 80ms to 17000ms and like 1mbps download.
I stopped the upload and tested within like 10seconds and everything was fine. I did this like 6 times and each time the same result, when I start the upload everything goes weird and after I stop it all goes back to normal.
I tried with torrents as well and even uploading at like 1 to 5 kb/second was enough to give me those results.
I have no clue what to do as like I said I have a fresh format with very little applications(no allwaysync or anything like that).
My computer is hooked up wireless so I can try with a Ethernet cable but other than that not sure what to do.