Great but... Rated 5 out of 5 stars

A great extension but ping doesn't work any more.
netError.js should be amended with this in const tools section:

"Ping": "http://dns-tools.domaintools.com/ip-tools/?query=" + window.content.location.hostname + "&method=ping" ,

While I'm at it I also prefer:

"Trace": "http://dns-tools.domaintools.com/ip-tools/?query=" + window.content.location.hostname + "&method=traceroute",

Mark

This review is for a previous version of the add-on (0.8.2).