This problem has been going on for a couple of months now. We've had our internet provider and the same setup for about 5 months before this with no problems. I first noticed this in gaming. My ping will stick to around 40-50 in a server, but continually spike to 80-100. I don't notice it all that much, but on others' screens I'm choppy and look laggy.
When I did a ping test to google.com in cmd, the same story as you can see here -
I'm connected to a router, but it seems to happen while directly connected as well. It has nothing to do with others on the network either. The modem is old, not sure if that has anything to do with it, a Motorola SB4200. After extensive research, the only answers I'm coming up with is that it's my ISP. Not sure why it would change all of a sudden, though.
A technician probably changed which port a cable plugged into back at the branch station. Unfortunately there's not much that you can do. Call the ISP, but I woudn't expect much out of them. Until you can show them that the connection drops that is.
They might be able to run a signal test from the tech center, or a connection on the cable lines might be getting corroded. Try unscrewing and resecuring all of the cable connections you have access to.