Dashboard Variables Issue

I’m using Promethues and Grafana for monitoring. (Monitoring 10 servers.)

In Grafana dashboard , under host it was listing the IP of the servers( 10 servers) which was mentioned under promethus.yml file.
It is difficult to identify the server with the host name.
I need to display the corresponding host name in the host or along with IP address i need to add some names to differentiate and understand it immediately.
Edited the varibale section and replace the label_values(node_load1, instance) with label_values(nodename).

But values(data) were not loading for that host. Reports as no data

Can anyone help me out ? how to fix this Issue.