Looks like there’s a problem with TADDM using the new 1.7.1 version of Cygwin as it’s SSH server.
http://www-01.ibm.com/support/docview.wss?uid=swg21419038&myns=swgtiv&mynp=OCSSPLFC&mync=R
So if you’re downloading Cygwin for a TADDM installation, use the link to the older, 1.5 version of Cygwin - http://cygwin.com/setup-legacy.exe
You could actually just rename the regular setup.exe to setup-legacy.exe and it will download the latest patch level of the older version of Cygwin.