I cannot find a way to start network interfaces with proper config after I changed config files (eg dhcpcd.conf). The only way I found to take the new config into account is to reboot. There must be a more elegant way. Though, service networking restart + systemctl restart dhcpcd.service + ip link set ethx down/up, don't work.
Update with info from comment:
To explain more, I change static ip declarations and don't want to reboot just for that.
sudo systemctl restart dhcpcd.service
usually works. You should explain in detail what you want to modify. – Ingo Nov 15 '19 at 17:46service networking restart
is long deprecated. Could you edit your question to make the commands you run more visible, add the error messages (or whatever it is you see that makes you say the commands don't work) and include the exact config changes. – Dmitry Grigoryev Dec 03 '19 at 12:56