Did you ever figure it out? I'm currently having the same problem.

Hey all,

So ive been in crypto for awhile but just purchased my first antminer. I hooked everything up, logged into my router, found the miners IP, entered in into url and entered root for the user and password but I keep getting the unauthorized error. Ive reset the miner several time and still no luck. Has anyone had this problem before? I'm out of ideas.