There are some troubleshooting steps I would like you to try but first I want to know some more information about your system configuration.
Please provide me with the system information report. How to get it?
System Information: Click Start> Type System Information> Click File> Export> Save File> Attach using Advanced Editor Options.
Thank you for sharing this information.
Please note that it is always expected that internet speed will decrease when using the Bluetooth at the same time.
Can you please try using 5GHz band?