Been using Wndows 10 preview from day one on a 'spare' laptop - and have to say it looks promising.
However, the laptop 'name' is MikesLaptop and this always showed up as the name when looking at connected devices on my router and in the Network list within Windows.
I then set up a Windows Backup - whereupon the device name changed to WIN-3EJFOKVPR8A when looking at connected devices on my router (Netgear R8000 Nighthawk), although it remains as MikesLaptop in the Network list within Windows.
Have had a look around the registry but can't find anything untoward. Have also done a clean install - but W10 unfortunately keeps all the old settings, even when asked to keep nothing!! (It is, after all, work in progress). I've fed it back to MS but don't expect any response - and no amount of googling comes up with an answer.
Before I go mad and reformat the disk, then do a clean install - anyone out there playing with W10 that might have any ideas??