Work VPN Slowing Home Network

Hey everyone,

New here.

Here is a basic rundown.

I have Centurylink 20mbps down 2mbps up.

I am a web developer and work from home. My wife is also working from home as a nurse and was set up with a cisco box, some type of gateway or something that connects directly to our modem then her phone connects to that along with her laptop.

We are always getting 16ms of ping and 20mbps down, no issue.

Randomly, and randomly, on saturdays or early on mondays, it will jump to 400ms and 0.5mbps making it impossible for her to work.

As soon as she shuts off her machine, the internet is back to 16ms and 20mbps down.

She is logging into a VPN and we talked with the tech support and they said there is nothing going on at all on their end but if we cut power directly to this box, the net is fixed.

Any ideas?