I also am no longer able to get my My Cloud EX2 Ultra to connect to AD either using same credentials I was using with OS 3. I’d be interested in the solution or if there isn’t one yet, perhaps what log I can be looking at to get insight into the issue on the My Cloud EX2 device using sshd.
I have spent literally days trying to figure that out.
Do you have on your EX4100 -by any chance- a Static IP with the fourth part above .128? Try to change it to something lower.
On my EX2 Ultra if I set the static IP above .128 I get the “Connection failed” message.
From .1-.127 I get successful connection.