Hi everybody, i have a problem during boot, i get a dhcpcd error that force me to wait 30/40 s every time.
As suggested i gave the command systemctl status dhcpcd@enp7s0.service and thats the output:

● dhcpcd@enp7s0.service - dhcpcd on enp7s0
Loaded: loaded (/usr/lib/systemd/system/dhcpcd@.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since gio 2016-10-27 10:23:43 CEST; 8min ago
Process: 421 ExecStart=/usr/bin/dhcpcd -q -w %I (code=exited, status=1/FAILURE)
ott 27 10:23:13 PC dhcpcd[421]: DUID 00:01:00:01:1f:a3:e7:39:b8:ca:3a:cc:1f:08
ott 27 10:23:13 PC dhcpcd[421]: enp7s0: IAID 3a:cc:1f:08
ott 27 10:23:13 PC dhcpcd[421]: enp7s0: carrier lost
ott 27 10:23:13 PC dhcpcd[421]: enp7s0: deleting address fe80::42cd:45b0:b9fd:d45c
ott 27 10:23:13 PC dhcpcd[421]: wlp8s0: new hardware address: 5e:1f:f8:72:88:28
ott 27 10:23:17 PC dhcpcd[421]: wlp8s0: new hardware address: 9c:2a:70:2a:74:97
ott 27 10:23:43 PC systemd[1]: dhcpcd@enp7s0.service: Control process exited, code=exited status=1
ott 27 10:23:43 PC systemd[1]: Failed to start dhcpcd on enp7s0.
ott 27 10:23:43 PC systemd[1]: dhcpcd@enp7s0.service: Unit entered failed state.
ott 27 10:23:43 PC systemd[1]: dhcpcd@enp7s0.service: Failed with result 'exit-code'.

So you're using this on a laptop I'm guessing? Have you got your wifi set up as well as ethernet? Or are you looking only to connect via ethernet?

Yep, I'm using an alienware m14x r2. My wifi network works really good out of box and also the ethernet. The only problem is the latency in boot becouse the dhcpcd fail.

If you're only using the wireless and not the ethernet you can just disable the service from start up. Paste the output of: systemctl list-unit-files | grep enabled

It would be impractical to disable the service because they often use the ethernet.
Anyway, that's the output of systemctl list-unit-files | grep enabled

org.cups.cupsd.path enabled
autovt@.service enabled
avahi-daemon.service enabled
bluetooth.service enabled
dbus-org.bluez.service enabled
dbus-org.freedesktop.Avahi.service enabled
dbus-org.freedesktop.ModemManager1.service enabled
dbus-org.freedesktop.NetworkManager.service enabled
dbus-org.freedesktop.nm-dispatcher.service enabled
dhcpcd@.service enabled
display-manager.service enabled
gdm.service enabled
getty@.service enabled
ModemManager.service enabled
NetworkManager-dispatcher.service enabled
NetworkManager.service enabled
nmbd.service enabled
org.cups.cupsd.service enabled
smbd.service enabled
avahi-daemon.socket enabled
org.cups.cupsd.socket enabled
remote-fs.target enabled

Your problem is that you have NetworkManager and dhcpcd enabled and running. You need to choose one or the other.

Ok, but how can i set up network-manager instead dhcpcd?

Ok, i gave the systemctl disable dhcpcd@enp7s0.service command but nothing changed.
And that's the output of systemctl --failed

UNIT LOAD ACTIVE SUB DESCRIPTION
● dhcpcd@enp7s0.service loaded failed failed dhcpcd on enp7s0

LOAD = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB = The low-level unit activation state, values depend on unit type.

1 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.