The slow download speed can be due to a poorly written driver. Try to brute force the problem, I think it will fix the problem. Have you performed the speed test? If not, try performing the internet speed test using an accurate tool. If you want to save your time, try checking this speed test tool Do these things to have an accurate result.
● Make sure that your router is only connected to one device before you start the speed test
● Close all the programs that are running on your browser and using the internet
● Repeat the test twice to have more accurate results
After performing the speed test, you will have a clear picture of why you are facing this problem and how to solve it.