hacks, relays, and back doors

A week or so ago, I started having problems getting online. Everything bogged down after about an hour or less. No Roku, no access from either laptop. It finally got bad enough that I called my ISP and requested tech support. They sent out a tech after going through a few routines over the phone. Before the tech arrived, I got a CD jammed into the DVD player, so took my laptop apart and then left. When I got back, the tech had been here, and everything was working well. I put together my laptop, plugged it in, and within 45 minutes, all went south again. Back came the tech the next day, and showed us that data were streaming heavily through the modem, and he declared that there must be a program using up all the bandwidth. Closing all browsers didn't stop it. However, closing network access to that computer did. Stopped it cold.

I've surmised that somehow, someone managed to hack my computer and use it as a relay. At the moment, I'm waiting for my second computer (Windows 7), which I'd put off repairing, to be fixed and ready to use, and at the moment I'm using my son's laptop. Earlier today, my buggy Windows 10 computer was on but not connected to the internet, and we again had problems with network access until I shut it down. Once I have my second laptop back, I'll be able to transfer some files to it and then do a clean install on the first, but I want to make sure this doesn't happen again.

What programs resident in Windows 10 that I need to stop permanently? What back door ports do I need to close? And how could a computer that's not connected to the internet still manage to be a problem with streaming??

rosawoodsii,

Not an expert in hacking issues, however, the following are some sources readily available for review if you are suspicious of hacking activity.

Inspect your PC by using Event Viewer logs. They may contain information of interest.

On Windows 10, search for: Event Viewer
Expand Windows Logs > Security
Look for anything suspicious.

To check whether anyone has been accessing your PC, again in Event Viewer:
Right click on System, select: Filter Current Log
In the the Event Sources drop-down arrow select: Power-Troubleshooter
Click: OK

In the list of all the times the PC was powered up, check under the Date and Time column, and click on questionable incidents for further information.

If you use Windows Defender, check its logs:
Click on History tab > View details

Also check the Windows Firewall > Advanced Security
Click to expand the Monitoring > Firewall

Also,

Once I have my second laptop back, I'll be able to transfer some files...

Make sure you scan your files with an AntiVirus like ESET Online Scanner!

Some online scanners detect existing AntiVirus software and refuse to run. You may need to disable your real-time protection of your existing AV, if you encounter a problem.

ESET Online Scanner FAQs #5
Online scanner FAQ—ESET Knowledgebase

Thanks, I'll look at all of those things.

Just finished the clean install, but what a headache and what a bad joke. I could go on a rant but I'll save it for another day.

Something was very strange about the computer. Even when it was not connected to the internet, it was still interfering with the bandwidth. Can someone explain that to me? Could a port be open, the computer have a back door, the modem itself have a back door? Now that the installation is complete, all seems to be well, but I don't understand how it could interfere with bandwidth just by virtue of being powered on, no internet access.

A possibility:

Change the Wi-Fi channel number to avoid interference:

https://www.lifewire.com/wifi-channel-number-change-to-avoid-interference-818208

Thanks. I have changed the channel previously, but this article gives me more things to look at. I appreciate the reference.

Sure hope you get the issue sorted out. Hard to figure out...