differentiate no connection and wrong password using pxssh in python

Question

I am testing how to differentiate between "no connection" and "wrong password" for ssh login. My ssh class is like the following

class SSH(object):
  def __init__(self, ip):
    self.ip = ip
  def connect (self):
    try:
      connection = pxssh.pxssh()
      connection.login(self.ip, "user", "password")
      print "success"
      return
    except pexpect.EOF:
      print "no connection"
      return
    except pxssh.ExceptionPxssh as e:
      print "wrong password"
      return

But it looks like in some cases even there is no ssh connection or connection timeout (such as ssh to a windows), it still throws the exception of pxssh.ExceptionPxssh instead of pexpect.EOF. But in other cases it works fine.

Could anyone give some advice what's the issue and how to fix?