<your search> | stats max(err) min(err) by host,fpc,ichip
edit:
* | stats max(err) as max_err min(err) as min_err by host,fpc,ichip | eval rate=(max_err-min_err)/720 | fields - max_err min_err | sort -rate
added to the answer
how do I sort it by host with highest rate ? rate is (max(err) - min(err)) / 720