We just got DELL R920 and installed Centos 6.5 on it. After installation, network not function. We manually enter IP address, gateway and netmark on "em1". we also do following: 1. startup NetworkManager 2. /etc/sysconfig/network-scripts/ifcfg-em1 ==> NM_CONTROOLED=yes I tried to startup network and get error message: Bring up interface em1: connection activation failed Device not managed by NetworkManager or unavailable. Any ideal? Thanks.