Hello,
I just installed Plesk (version 17.8.11) on Debian 9.4 and I am in the impossibility to add IP addresses.
I have an error message: "ifmng failed: /etc/network/interfaces: No such file or directory"
**** - Plesk only supports Debian 8 and Ubuntu 16.04 servers running the ‘systemd’ init system. Compatibility with ‘sysvinit’ has not been tested and is not guaranteed.