When using systemd-networkd in conjunction with the wpa_supplicant@.service or an driver specific equivalent. There are some issues on shutdown. Services using internet connections (such as ssh) don't shut down their connections gracefully, which results in hanging ssh-sessions rather than closing them normally. A more major problem, remote mounts can't be unmounted safely and result in the system hanging for 90 seconds.

This issue doesn't occur with NetCTL and is related to the systemd unit config.
I added Before=network.target to my wpa_supplicant@.service, and this fixes the issues I'm having. When sending a reboot to the server, the SSH session is closed instantly and remote folders unmount safely. Than, systemd-networkd shuts down, and wpa_supplicant after systemd-networkd, as it should be.
I've read that tthere are people against adding Before=network.target to the services, but I think it could be very helpful. Any thoughts on this?