I could no longer log in to my RT-N66U (it wouldn't accept old info) so I did 30 sec. reset to factory settings. I then saw that new firmware was available so I downloaded and installed it. After re-entering all the info into the router I noticed that the 5.0 band wireless speed had dropped from 125mbps to less than 20 mbps. After changing the 5.0 bandwidth to 40 I got up to 30 mbps. I used to get 125 mbps on 5.0 wifi. Any help would be appreciated.