Ping increases drastically randomly

Hello,

So I am having an issue where while I am gaming, at random times, for no reason, my ping shoots up to 5000 for about 30 seconds, then comes back down. Which often causes me to be removed from matches. I have spoken with 2 agents, one agent two times. The first agent concluded that it was due to me being over my usage 1.2 terabyte limit, which I thought was the cause since I've had similar issues in the past with the same cause, so I upgraded, but that wasn't the case this time. I spoke with the second agent, he told me that he synced my modem with the gateway and that the issue wouldn't occur anymore. Five minutes later, it happened once again. I was able to get reconnected with the same agent and was told to wait 10-20 minutes, a day later, it's still happening, just less often, which is still an issue. I use a ethernet cord from my modem to a Nighthawk router, which uses another ethernet cord to my computer, this is due to the fact that the ethernet cord that I originally purchased was about an inch short of my computer, and it was the longest in stock at the time.