Goal: Assign a static IP to the Ubuntu server so it remains the same across reboots, allowing consistent SSH access from other devices. Problem: router DHC, Ubuntu server uses cloud-init, which can override the manual network settings after reboot.

1. Check Network Interface

ip a

• Find the Ethernet interface connected to your router

• Example output

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host noprefixroute valid_lft forever preferred_lft forever 
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000 link/ether 00:e0:4c:64:d4:90 brd ff:ff:ff:ff:ff:ff altname enp3s0 inet 192.168.1.*/24 metric 100 brd 192.168.1.255 scope global dynamic ens33 valid_lft 86151sec preferred_lft 86151sec inet6 2400:1a00:b030:29c2:2e0:4cff:fe64:d490/64 scope global dynamic mngtmpaddr noprefixroute valid_lft 949sec preferred_lft 949sec inet6 fe80::2e0:4cff:fe64:d490/64 scope link valid_lft forever preferred_lft forever

✅Interface name to use: ens33

2. Disable Cloud-init Network management

   Cloud-init may reset network changes on reboot. Disable it permanently:

sudo bash -c 'echo "network: {config: disabled}" > /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg'

3. Configure Static IP with Netplan

   1. Open Netplan config file Netplan configuration file location is set to /etc/netplan/ directory. Depending on your Ubuntu installation Netplan configuration file can take one of the following three forms:

      • 01-netcfg.yaml

      • 01-network-manager-all.yaml

      • 50-cloud-init.yaml Now, open your configuration file:

        sudo vim /etc/netplan/50-cloud-init.yaml

2. Replace the content with:

    network:
        version: 2
        ethernets:
        ens33:
            dhcp4: false
            dhcp6: false
            addresses:
            - 192.168.1.*/24
            routes:
            - to: default
              via: 192.168.1.254
            nameservers:
                addresses: [8.8.8.8, 1.1.1.1]

• Replace:

  • ens33: your interface name

  • 192.168.1.* -> desired static IP (outside router DHCP range)

  • 192.168.1.254 -> your router's gateway IP

4. Apply the configuration

sudo netplan apply

• If using SSH, be aware that your connection may drop when IP changes.

• Verify new IP:

ip a
ping -c 4 8.8.8.8

5. Test SSH access from another device:

ssh <username>@192.168.1.*

• Confirm you can connect with the new static IP

6. Verify Persistence

• Reboot server

sudo reboot

• Check that the static IP is still active

ip a

7. Tips / Notes

• Always pick a static IP outside your router's DHCP range to avoid conflicts

• Using cloud-init disable ensures manual network config is persistent.

• You can also add extra DNS servers if needed.