Network goes down repeatedly

Greetings all,

I've setup a server with redhat v7. No matter what I do after a couple a hours, it always become unreachable by ssh, by http basically refusing all connection. After which I issue a network restart command to bring it back up.

I've read a little bit about NetworkManager and how to disable it but it did not help.

The settings I've tweak are the firewall-cmd in the permanent public zone to allow ssh and http and also the selinux policies to allow tomcat to network-connect and read/write to certain context.

Does anyone knows what make my network policies fall every time I restart the network service after a couple hours ?

Thank you,
Simon