Did you ever find your miners IP or find a solution? Im having the exact same issue with one of my Dragonmint T1's as well. Can't find the IP anywhere when scanning my network. I actually had this issue with another T1 first. It dropped offline today so I went to my farm to see why and couldn't find the IP address when scanning the network. I tried some basic troubleshooting and figured it could be a bad control board. I had a spare Dragonmint with a few bad hash boards that I use for parts so I swapped out the control board from that. My network must have assigned a new IP and I was able to log in and get that one set up. However, literally like a minute later I had another Dragonmint T1 drop offline with the same issue.   I could no longer log in to the miner with the IP that it previously had. I did a reset and scanned the network multiple times and have been unable to find it.

I haven't had a chance to run through any of these possible solutions for finding it. I don't have the patience for it tonight but Im wondering if it is maybe my router not having enough IP addresses allotted to assign. I have a pretty large farm at the moment and I just added a few more miners the past couple of days so maybe that is the issue.