having bad connection for the past week or so

hello all for the last week or so ive been having some really bad download speed and connection drops. my download is supposed to be 300 down and currently im getting .6-4 download. ive tried changing outlets redoing the coaxal cable configuration(using cable from else where in the house/ changing the one coming out of the router to a splitter and the wall etc) changing ethernet cables and obviously restarting my modem and sending reset signals. i checked a bit ago and my snr for downstream is low only hovering in the mid 20s i could really use some help here i just want to play some games uninterrupted lol