OCI: Unable to SSH to Linux instance “ssh: connect to host port 22: Connection timed out”

Applies To: 

Oracle Cloud Infrastructure - Version N/A and later 
Linux x86-64 

Symptoms 

Unable to SSH to OCI Linux instance with following error but able to connect to  via serial console using password. 

$ ssh -vvv -i id_rsa_admin opc@10.x.x.x 

OpenSSH_7.4p1, OpenSSL 1.0.2k-fips 26 Jan 2017 

debug1: Reading configuration data /etc/ssh/ssh_config 

debug1: /etc/ssh/ssh_config line 58: Applying options for * 

debug2: resolving "10.x.x.x " port 22 

debug2: ssh_connect_direct: need priv 0 

debug1: Connecting to 10.x.x.x [10.x.x.x] port 22. 

debug1: connect to address 10.x.x.x port 22: Connection timed out