systemd-networkd 'relaytarget' not working (dhcp relay) in Debian stable 12 bookworm

my first question here. I'm currently using the 'dhcp-helper' program to do dhcp relay, works fine, but I want to switch to using the systemd-networkd 'RelayTarget' function in the *.network file. I've tried every option I can think of, but can't seem to get it working. * Running current Debian stable "bookworm 12" 6.1.0-13-amd64 * Debian stable runs systemd 252 (252.17-1~deb12u1) I've tried every option I can think of, no luck yet. /etc/systemd/network/02-port2-lan0-static.network:

# /etc/systemd/network/02-port2-lan0-static.network
# configures lan0 with static ip address
#
[Match]
Name=lan0
[Network]
Address=172.16.1.1/24
# do not set gateway or dns, will inherit from system
[DHCPServer]
ServerAddress=172.16.11.2/24
RelayTarget=172.16.11.2
BindToInterface=no

Anyone have this working in Debian stable? I realize Debian stable does not run the latest systemd version. This is a production router, so upgrading to testing is not an option. Thanks