On redhat 7.4 wireguard not working

[Germano Massullo]

I am using Wireguard on CentOS 7.4 by many months
iproute-3.10.0-87.el7.x86_64
wireguard-dkms-0.0.20180413-1.el7.centos.noarch
wireguard-tools-0.0.20180413-1.el7.centos.x86_64

$ dkms status
wireguard, 0.0.20180413, 3.10.0-693.21.1.el7.x86_64, x86_64: installed

In my system, Wireguard network interface is handled as a systemd service

# systemctl status wg-quick at wg0.service
● wg-quick at wg0.service - WireGuard via wg-quick(8) for wg0
   Loaded: loaded (/usr/lib/systemd/system/wg-quick at .service; enabled;
vendor preset: disabled)
   Active: active (exited) since gio 2018-04-19 18:07:01 CEST; 1h 1min ago
     Docs: man:wg-quick(8)
           man:wg(8)
           https://www.wireguard.com/
           https://www.wireguard.com/quickstart/
           https://git.zx2c4.com/WireGuard/about/src/tools/wg-quick.8
           https://git.zx2c4.com/WireGuard/about/src/tools/wg.8
  Process: 1059 ExecStart=/usr/bin/wg-quick up %i (code=exited,
status=0/SUCCESS)
 Main PID: 1059 (code=exited, status=0/SUCCESS)

apr 19 18:07:00 vpn systemd[1]: Starting WireGuard via wg-quick(8) for
wg0...
apr 19 18:07:00 vpn wg-quick[1059]: [#] ip link add wg0 type wireguard
apr 19 18:07:01 vpn wg-quick[1059]: [#] wg setconf wg0 /dev/fd/63
apr 19 18:07:01 vpn wg-quick[1059]: [#] ip address add **removed by me**
dev wg0
apr 19 18:07:01 vpn wg-quick[1059]: [#] ip link set mtu 1420 dev wg0
apr 19 18:07:01 vpn wg-quick[1059]: [#] ip link set wg0 up
apr 19 18:07:01 vpn systemd[1]: Started WireGuard via wg-quick(8) for wg0.