@Kevin_Z My internet service provider is RCS & RDS Romania and the bandwith I paid was 1200 Mbps total. Yes, other devices work for ex. My phone, my family member's devices, and my OS is Windows 10....

A few months ago I got a new router. I setted it in, etc. then i start using it. For my family it works well, but for me, it doesn't. a few weeks later i decided to give it a test on ookla speedtest....