OCI : Ubuntu instance is not accessible as router IP doesn't persist after reboot

Applies TO: 

Oracle Cloud Infrastructure

Linux OS

 

SYMPTOMS 

Unable to access the ubuntu 22.04 instance as it loses router IP provided by DHCP for every reboot 

 

CAUSE 

Ubuntu instance lost the router IP after reboot 

 The ip route command doesn't show the default router IP and its missing  

root@host:~# ip route 
10.10.**.***/26 dev ens3 proto kernel scope link src 10.**.**.*** 
root@instance:~# 

 Observed that dhclient -v command provides router IP from dhcp, but router IP gets removed for every reboot 

The instance network configuration was managed by NetworkManager service and netplan.conf file was missing there 

root@host:~$ ls -l /var/run/NetworkManager/conf.d/netplan.conf 
ls: cannot access '/var/run/NetworkManager/conf.d/netplan.conf': No such file or directory