I have a mystery, which I hope that someone can help me solve, please. I have a FritzBox 7590 provided by 2degrees. I don't go into it's GUI that often but attached a new repeater during the week and noticed a device called "Client" using it.

When I click through, I get a login request. I've tried a few of my obvious passwords and they don't work. I've been scratching my head as to what it could be. I've tried to eliminate all of the devices we have running. I've asked Mr Google for help but can't get an answer that makes sense to me. Does anyone know what this could be, please?

Here's some more detail from the Fritz GUI: