First, it's not unusual to see what you're seeing. Sometimes, one device is simply better at hogging bandwidth. In the meantime, see if the suggestions below make things better.
Antivirus software can cause this.. Try disabling or uninstalling it temporarily to see if it fixes the issue.
Tried updating your network adapter software? Checking for an updated driver for the problem computer's network adapter might help.
If the problem computer is Windows 10, have you tried turning off the "Delivery Optimization" option which shares Windows Updates with other computers on your network.
Hope this helps.
Hi - I'm hoping somebody can help because I'm not sure what else to do. All devices in my home are running off of wifi. My PC is returning download results of under 10mbps. I have a laptop that is returning 100mbps and my smart TV works fine. The weird thing is that the task manager is not indicating any additional network bandwidth is being used when these results are being returned. I've adjusted the Windows update bandwidth down to 6% with no improvement. Any assistance would be greatly appreciated. Thank you!