Well, what is your ISP and the plan you have? (if you don't mind).
If you are not comfortable telling the info, then restart your router, upgrade your router maybe, try placing your router in a better location. Run some speed tests throughout the day. It might be a congestion issue or something.
Check if your computer/devices don't have any background tasks running.
Turn off any VPNS before testing speed test.
Change DNS to 1.1.1.1