Powerterm won't connect after upgrading to LR12.5 and Windows Server 2012

One of our tests  connects to a VMS node with ssh using the RTE protocol and powerterm. The connection works on our old server, which is Windows Server 2003 using LR 9.5.0.0.

From the new server, I can telnet/ssh into the VMS node using windows telnet without issue, but powerterm can't connect. From the VMS node, we see a protocol error from the attempted connecton.