The MAC address is for a device made by Hon Hai Precision and a quick Google says this:
Hon Hai Precision Industry Co., also known by its trade name, Foxconn, is the world's largest contract electronics manufacturer. It makes mobile phones, computers, servers, and TVs. Other products include components such as connectors, cable assemblies, enclosures, flat-panel displays, game consoles, and motherboards.
So it could be anything really 😆
Yeah - I got that far - its on my wifi and I cant disconnect it.....how can I force that?
What does the green "D" mean?
I've seen these sometimes on various networks, and found them to be mostly printers, often HP. They appear as part of the "direct print" features such devices have. But as others said, could be many things. Is it there all day, which suggests something infrastructural, or comes & goes which would suggest something mobile. The 2.4GHz suggests it is not something needing a high data rate.