I started with using EDMC 3.50 and later updated to EDMC 3.51, both earlier pre-release beta. When I upgraded from 3.50 to 3.51,I had the same issue. I just updated to 184.108.40.206 and got it again. How I resolved this in the past: even though EDMC was still communicating with Frontier, I went to the Frontier authorization site, logged in, and removed the key for EDMC. EDMC requested it again and after that I got TCE to communicate again.For EDMC 220.127.116.11, which is a pre-release beta, unfortunately TCE is not working. I get a status error in TCE for EDMC. Don't know if this is a local error on my machine or true for all users of this version of EDMC. I should add that, same as previous post, 3.7 seemed to work.
However, right now, I try to pull up the authorized keys after logging in and get an error.