Sorry about this could be FAQ but I did not find any useful information on Internet/Google. I setup a 4G/LTE modem on a Ubuntu 18.04 and it is verified by "sudo pon/poff provider".
The next step could be similar to:
/etc/network/interfaces
allow-hotplug ppplte0
iface ppplte0 inet ppp
provider isp
sudo ifup --allow=hotplug ppplte0
sudo ifquery --state ppplte0
sudo ifdown ppplte0
Any equivalent set-up by netplan? For if{up/query/down} commands, I would like to put it into systemd to start/stop when system is boot-up or shutdown.
Thanks for any comments.