Internet speeds bad in 1 room but amazing in others?

Hi,

I have a small network n my house. One room on the main floor has my cable modem, and router. My basement (Less than 75ft away) the download speeds are HORRIBLE 60 k/s max, BUT the main computer next to the router is getting the full 20mb/s that it should be? It’s connected with Cat5 cable and total wiring is far less than the 328ft max. Any Ideas?