21.10: NetworkManager's OpenVPN client: how to set 'ifconfig-push'

I am trying to configure OpenVPN clients with a fixed IP address. I think there are two main approaches: ifconfig-pool-persist on the server or ifconfig-push on the client. After some difficulties in making ifconfig-pool-persist work, I decided to try the ifconfig-push approach.

My OpenVPN clients are Ubuntu laptops (21.10 for instance), so we are using NetworkManager's OpenVPN configuration.

My issues:

• In NetworkManager's OpenVPN GUI, I cannot find a way to add the ifconfig-push option.
• In NetworkManager's OpenVPN configuration files, I cannot find where to put the ifconfig-push option.

As far as I understand, the configuration files are in /etc/NetworkManager/system-connections. I took an example.ovpn file online and imported it in the GUI, which generated a /etc/NetworkManager/system-connections/example.nmconnection file looking like this:

[connection]
id=example
uuid=183aaf3d-6974-41e7-abea-f4d0b3ae1a41
type=vpn
permissions=
[vpn]
ca=/home/bibi/.cert/nm-openvpn/example-ca.pem
cert=/home/bibi/.cert/nm-openvpn/example-cert.pem
cert-pass-flags=0
cipher=BF-CBC
comp-lzo=adaptive
connection-type=tls
dev=tun
key=/home/bibi/.cert/nm-openvpn/example-key.pem
ping=10
ping-restart=120
port=1194
remote=example.com
remote-cert-tls=server
ta=/home/bibi/.cert/nm-openvpn/example-tls-auth.pem
ta-dir=1
service-type=org.freedesktop.NetworkManager.openvpn
[ipv4]
dns-search=
method=auto
[ipv6]
addr-gen-mode=stable-privacy
dns-search=
method=auto
[proxy]

Adding an ifconfig-push rule to the example.ovpn file before importing did not result in any change of the example.nmconnection file.

Is this setting entirely ignored?

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