CentOS - Feb 2017 - Network conections problems

Hi;
 I have a CentOS 6.8 x86_64 server where just run Oracle 11g 64 bit data base
server. Is happen that sometimes it loose all connections (no ping, I can not
access via ssh, no TNSping of Oracle server have success). When this happend I
make ping from this server to some IP address of my network and then everything
work fine again. I check logs looking for some mistake or problem in the network
device, but I do not find anything or maybe I not looking where must be.
 I check that from a workstation (Windows XP or Windows 7 or Windows 10) when I
make ping to the server, after ~ 8 seconds in get answer and always the first
one is loose. If you try again ping, everything work fine (no answers are loose)
 
C:\Users\administrator>ping pgtm.gtm.gob.cu

Haciendo ping a pgtm.gtm.gob.cu [192.168.41.4] con 32 bytes de datos:
Tiempo de espera agotado para esta solicitud.
Respuesta desde 192.168.41.4: bytes=32 tiempo<1m TTL=64
Respuesta desde 192.168.41.4: bytes=32 tiempo<1m TTL=64
Respuesta desde 192.168.41.4: bytes=32 tiempo<1m TTL=64

Estad?sticas de ping para 192.168.41.4:
    Paquetes: enviados = 4, recibidos = 3, perdidos = 1
    (25% perdidos),
Tiempos aproximados de ida y vuelta en milisegundos:
    M?nimo = 0ms, M?ximo = 0ms, Media = 0ms

This are some of the configs related with networks

[root at pgtm ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
TYPE=Ethernet
UUID=11dcddd4-6530-457a-8d3e-01a8339fb113
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=none
HWADDR=6C:92:BF:26:C7:02
IPADDR=192.168.41.4
PREFIX=24
GATEWAY=192.168.41.1
DNS1=192.168.41.17
DOMAIN=gtm.gob.cu
DEFROUTE=yes
IPV4_FAILURE_FATAL=yes
IPV6INIT=no
NAME="System eth0"

cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.41.4 pgtm pgtm.gtm.gob.cu

[root at pgtm ~]# cat /etc/resolv.conf 
# Generated by NetworkManager
search gtm.gob.cu
nameserver 192.168.41.17

[root at pgtm mail]# cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=pgtm.gtm.gob.cu
GATEWAY=192.168.41.1

 Someone that happend something like this, or some place for where keep looking
to try to fix this loose of conection?
 Thank and sorry for my horryble English.
 
Rommel Rodriguez Toirac
rommelrt at nauta.cu

First guess is that you may have two devices on the network with the
same ip address.

Next time this happens, try doing

1. 'arp -n' from a machine other than the db server
2. ping the other machine from the db server, then
3. 'arp -n' from the other machine

Compare the outputs of the two invocations of arp. If the outputs show
different MAC addresses for 192.168.41.4 then you have two different
devices with the same IP address.