You might try enabling debugging in both the server and client:
On the server, run sshd on a different port:
Code:
sudo /usr/sbin/sshd -dddp 2022 2>&1 |tee /tmp/sshd.log
Then on your client connect with
Code:
ssh -vvvp 2022 server 2>&1 |tee /tmp/ssh.log
-or-
Code:
scp -vvvp 2022 server:/file /tmp/file 2>&1 |tee /tmp/scp.log
Might give some clues, even if just a debug string which happens when the connection is shut down, which might turn up something else on a web search....