Strange Network Behavior in CentOS on Dell PowerEdge R320

Question

Computer networks

Hello everyone, something strange is going on with the network. Installed CentOS on this server, set up a network with a static IP of the internal mesh, disabled IPv6. I reboot and there is no ssh connection, I go directly to the server and ifconfig gives
em1 Link encap: Ethernet HWaddr xxxxxxx
inet6 addr: xxxx... WHERE is he from?

I do /etc/ini.t/network restart
all interfaces are successfully deactivated, but em1 can no longer be activated
Error, some other host already uses address 192.168.0.12

For the first time I encounter this.
Network Broadcom Gigabit Ethernet BCM5720

Answer 1

pre-up sysctl "net.ipv6.conf.all.accept_ra=0"
pre-up sysctl "net.ipv6.conf.default.accept_ra=0"
pre-up sysctl "net.ipv6.conf.em0.accept_ra=0" »
If the address is Global.
If local - then it makes no sense to tear it off.