"Unknown" listed as device name on my rotuer's DHCP list

I have an Archer C8 wireless router. Most of my devices, when connected, show up on the DHCP list with the name I assigned them for easy recognition; for example I named my iPhone "Eldram's iPhone" and when its connected to the router I see it listed as such. Now, a few devices I own that I have assigned similar names show up as "Unknown" even though I have named them; specifically the family desktop PC (Windows 7) is called "Eldram Family PC", my PS3 is "Eldram's PS3" and similar...

"Unknown" listed as device name on my rotuer's DHCP list