Incredibly slow internet speeds on Preferred plan using Motorola Wireless Cable Modem

Hi,

I was just hoping to find a way to increase my download and upload speeds. I just moved into an older neighborhood near ASU and I am not sure if the area is causing the slow speeds, or my new wireless cable modem, the Motorola SBG6580. 

I used the speed checker tool and it's been showing download speeds never above 1.5Mbps while I was expecting at least 20Mbps on the Preferred plan which advertises 25Mbps speeds. I am not sure what the issue may be, let me know if there is any more information needed to help find a solution!

Thanks!