It looks like something similar when I had changed the IP and didn’t finish configuring everything. I had left out checking and configuring the Storage group/nodes.
If you have changed your IP(or maybe even Server name) try following these instructions: https://wiki.fogproject.org/wiki/index.php/Change_FOG_Server_IP_Address
The key part I missed(becasue I didn’t really use storage nodes) was:
Update the IP address for the storage node on the FOG system where you changed the IP address - Web Interface -> Storage Management
Make sure you actually click the node and check the IP setting.
that line in the bandwith.php file points to a location in /sys/class/net/<net_adapter_name>/operstate
I’m not sure if CentOS is diferent but my adapter name is eth0 so look for that in place of adapter name.
Im not sure if you can simply recreate it it if it doesn’t exist. It simply appears to display whether or not your adapter is up or not.