Network is lost for KVM VPS once it is re-configured via SolusVM web interface

Symptoms 

Network is lost for KVM CentOS 7 VPS once it is re-configured via SolusVM web interface

CentOS 7 guest OS was installed via ISO image

Cause

When guest OS was installed via ISO image it has new network interface name like ens0. SolusVM is hard-coded to operate with old names like eth0. Once it is reconfigured via web interface a non-working ifcfg-eth0 interface is created inside guest OS and it causes broken network service

Resolution

There are 2 options how to deal with this setup:

Option 1 is restore old ensX configuration file, remove ifcfg-eth0 configuration file and avoid using Re-Configure feature in SolusVM for such VPSes

Option 2 is a switch from new NIC names to old ones:

1. Access VPS guest OS command line via VNC console
2. Edit file /etc/default/grub and add net.ifnames=0 biosdevname=0 to line with GRUB_CMDLINE_LINUX parameter:

   CONFIG_TEXT: GRUB_CMDLINE_LINUX=" crashkernel=auto net.ifnames=0 biosdevname=0 rhgb quiet"

3. Regenerate a GRUB configuration file and overwrite existing one:

   # grub2-mkconfig -o /boot/grub2/grub.cfg

4. Verify that there are no ifcfg-ensX network configuration files in /etc/sysconfig/network-scripts/ directory, only ifcfg-ethX with correct configuration in it
5. Reboot VPS