I recently upgraded from cable internet to fiber. I am paying for 1 gbps internet. I have a Linksys WRT 1900AC router that is supposed to be gig speed compatible. I have the router configured to have both 2.4GHz and 5GHz networks, on channels 6 & 153 respectively. On the 5GHz wifi, the maximum download speed I can achieve is 250mbps, and the 2.4GHz maxes out around 80mbps. What gives?