(Author here.) That’s missing from the article. But I have logs of the network. There’s nothing out of the ordinary. “I don’t know what I did wrong,” as I started the article, means “I’ve checked logs and such and there’s no indication of anything wrong on my end.”

A task that would be made much easier and less likely to miss something if the affected person had some indication as to what the problem was.

Do you expect the average user to know how to "eliminate the possibility that a device on their network is compromised"? That is untenable.