Gentler way to state failure.

Long story short, a project at work is taking major political heat for failing when we try to do something to computers. If those devices are not connected to the network, they will show up as failures on our reports. I am looking for a single word or short phrase that shows we didn’t fail, the machine was simply unreachable. Unreachable or disconnected are both terms that seem too vague. I also don’t want to be too verbose, since it will be a column in a spreadsheet.