By default Ubuntu desktop does not have ssh server enabled or installed , so we need to install openssh to get it enabled or you may get error like “Network error: Connection refused”
1.On your Ubuntu side, open a terminal by pressing Ctl+Alt+t , then run below command to install openssh-server

sudo apt-get install openssh-server

2.Optional you can check the running status of the ssh server service with below command

sudo service ssh status

The ssh server configuration file locates /etc/ssh/sshd_config in case you want to customize your ssh server configuration.

3.Now you should be able to ssh to your ubuntu machine ,good luck