Erratic Mouse Movements

I have a Certified Data PC desktop made by London Drugs. it is an excellent computer and gives me no trouble. I also have an HP desktop, and a MSI Laptop. All have windows 10, All have extended security updates from Microsoft up to Oct 13, 2026. 10 weeks ago i started having erratic cursor movements on my screen on the Certified Data when using my USB mouse. About once or twice a day for about 5 to 15 minutes when i try to use my mouse the cursor would move erratically on the screen and very difficult to click on anything when I tried to move it or click on something. To stop this, I cleaned the mouse, cleaned the desk, and checked the mouse batteries. All were good and didn't make any difference. My next solution was to unplug the ethernet cable (none of my computers use wifi). The erratic movements immediately stopped and I could move my mouse smoothly all over the screen. This led me to believe that this problem came from the modem or a hacker. I phoned ESET about this, they did an evaluation and found nothing. Then I hooked up my HP desktop. Same thing. Erratic mouse movements. Then I transferred to my Laptop and so far no erratic mouse movements. So I am perplexed. Does anybody have any suggestions as to how I can stop the erratic behavior? Thank you so much in advance.