Setting a Static IP in HassOS

Notes

mkdir -p /mnt/boot/CONFIG
vi /mnt/boot/CONFIG/my-network

Change the [IPv4] section to:

[ipv4]
method=manual
address=10.20.30.40/24;10.20.30.1
dns=1.1.1.1;8.8.8.8;

# nmcli con show
# nmcli con show "Home Assistant OS default"

# nmcli con edit "Home Assistant OS default"

nmcli> set ipv4.addresses 10.20.30.40/24
Do you also want to set 'ipv4.method' to 'manual'? [yes]:

nmcli> set ipv4.dns 1.1.1.1,8.8.8.8
nmcli> set ipv4.gateway 10.20.30.1

Confirm the changes:

nmcli> print ipv4

and Save:

nmcli> save

Restart the connection:

nmcli con reload

or a Host reboot also works.