For years my network stack has been based around ifupdown and wpa_supplicant but after a recent experience fighting them I decided to look to see what Buster offered and came out with a pretty nice new stack.
Old stack: ifupdown, ifplugd, dhcpcd, wpa_supplicant, resolvconf, unbound
New stack: systemd{-networkd,-resolved} + iwd [+ networkd-dispatcher]
The new setup has systemd-networkd network device setup,
networkd-resolvconf handling DNS lookup and caching, networkd-dispatcher
dealing with up/down hooks and iwd handling the wifi negotiations. It all
works surprisingly well and the setup was very simple. Be sure to stop and
disable whatever you are currently using to avoid conflicts.
Install the one missing piece.
$ apt install iwd
Configure ethernet and wifi... (replace and with appropriate names)
$ sudo tee /etc/systemd/network/eth.network > /dev/null << EOF
[Match]
Name=<eth>
[Network]
DHCP=yes
[DHCP]
RouteMetric=10
EOF
$ cat >> /etc/systemd/network/wifi.network << EOF
[Match]
Name=<wifi>
[Network]
DHCP=yes
[DHCP]
RouteMetric=20
EOF
Enable and start up networkd/resolved.
$ systemctl --now enable systemd-networkd.service
$ systemctl --now enable systemd-resolved.service
Sym-link /etc/resolv.conf to resolved's generated one.
$ ln -s /var/run/systemd/resolve/stub-resolv.conf /etc/resolve.conf
Use iwctl to connect to wifi (https://wiki.archlinux.org/index.php/Iwd)
Note these can mostly be run as a standard user
$ iwctl device list
$ sudo rfkill unblock <wifi> # needed once after boot
$ iwctl station <wifi> scan
$ iwctl station <wifi> get-networks
$ iwctl station <wifi> connect <ssid>