RuntimeError: YClientError: Could not connect to x.x.x.x: Session status: Undefined

[arynair]

(test_venv) root@8ff5eb066f2e:/root/container/test_venv# python t
ry1.py
Trace: Unable to connect to 172.18.87.54:830 over IPv4 (Connection refused).
Connection error occurred: Unable to connect to 172.18.87.54:830.
NetconfSSHClient: NC session status: -1
Could not connect to 172.18.87.54: Session status: Undefined
Traceback (most recent call last):
File "try1.py", line 28, in
protocol="ssh")
File "/root/container/test_venv/lib/python3.6/site-packages/ydk/providers/netconf_provider.py", line 48, in init
protocol, on_demand, common_cache, timeout)
RuntimeError: YClientError: Could not connect to 172.18.87.54: Session status: Undefined

I am getting this error. i have followed the steps here : https://community.cisco.com/t5/yang-development-kit-ydk/netconfserviceprovider-is-not-able-to-establish-ssh-tunnel/td-p/3585193 but was not able to am still getting this error

i am able to login to the router via cli using : ssh -2 -s username@172.18.87.54 netconf -p 830