I'm not going to pretend I know the possibility of what I'm about to say, but is it per chance possible?
My ISP has this thing called 'Global Mode', where my country's IP addresses don't get flagged as ours - it relies on their DNS settings - so it looks as if the user is not from my country but instead American so we can go to sites such as Hulu and Netflix etc. Now, with SecureDNS off, the issue (the connection 'mark.handbookforhandymen.com') has not come back, but instead there was another one that had the same DNS and/or ISP in the 'Get Details' thing. I currently have the secure DNS off, and it has nothing other than what I expected to be there (connection wise - Chrome extensions etc). However, when I turn the SecureDNS on, it all goes back to there being a weird connection much like the mark.handbook... but instead it's I think the IP address and the ISP and more all in the name, which reminds me of the DNS I get when I google it for my ISP (ie they're similar, IP address and ISP name in the name of it).
Is it possible this is just a conflict between my ISP's DNS and the SecureDNS?
note; if any of this makes no sense please don't hesitate to tell me to shut up - because as I said, I don't know anything about this.