Recent edits to pgl
So I take it from your edit/comment that am mistaken in thinking that ufw depends on a more generic 'iptables.service'? If so, one would need the following if using ufw:
. include /usr/lib/systemd/system/pgl.service After=ufw.service
@Graysky: Indeed. While based on iptables, ufw and shorewall load their rules through a script called by their .service files without ever relying on iptables.service capabilities. I chose ufw to illustrate the After= example because I thought its users might need the nudge more than the iptables and shorewall crowds.