Renaming of 192.168.1.20 failed . Does your web server have permission to modify the rrd files?

First thing to check is verify that the IP address is not already being monitored.

If you are getting the above error while trying to rename a device in LibreNMS, you may need to rerun some of the SELinux commands from the installation.

SSH into the server and run

restorecon -RFvv /opt/librenms

Now try renaming the device. Note that you can’t rename the device if the name/ip to a name that is being used by a different device.

If you continue to have issues, check the permissions from the installation guide (Official guide here)

You can also check for SELinux errors with

audit2why < /var/log/audit/audit.log

More SELinux info here