Replying to Odd internet connection help please

In my house we have two desktops and my laptop. When my laptop is off, the modem shows full internet connection, and everything is working perfectly fine, but as soon as I turn on my laptop, the internet speed crashes very significantly (it took at least two minutes for the page to load to type this.) We are not using Wireless.

Does anybody have any idea how to stop this? I have checked, there are no viruses on my computer, at least that my antivirus software can detect.

Thank you so much for any help.