unable to connect mongodb via robo3T from my system

I followed multiple tutorials to connect mongodb in my droplet via robo3T

I was trying to connect via ssh(entered username and password)

my mongodb.conf

  GNU nano 4.8                                       /etc/mongodb.conf                                                  # mongodb.conf

# Where to store the data.
dbpath=/var/lib/mongodb

#where to log
logpath=/var/log/mongodb/mongodb.log

logappend=true

#bind_ip = 127.0.0.1


#port = 27017


# network interfaces
net:
    port: 27017
    bindIp: 0.0.0.0   #default value is 127.0.0.1

security:
    authorization: enabled

root@nodejs-ubuntu-s-1vcpu-1gb-sfo-01:~# sudo ufw status
Status: active

To                         Action      From
--                         ------      ----
22/tcp                     ALLOW       Anywhere
Nginx Full                 ALLOW       Anywhere
OpenSSH                    ALLOW       Anywhere
22                         ALLOW       Anywhere
Nginx Full (v6)            ALLOW       Anywhere (v6)
OpenSSH (v6)               ALLOW       Anywhere (v6)
22 (v6)                    ALLOW       Anywhere (v6)

Robo3T is always throwing this error

Error:
Error when starting up SSH session: -8