Ok I've managed to get it to revert to the original default system name from the main menu by just hitting enter, and then reboot.
I can live with this original system name though I'd really like to rename it, and that also brings up the question of why it ever became named (none), I never entered that or chose that as a name at any point.
EDIT: I've now managed to get a custom name to be accepted, apparently by not using any capital letters or spaces. That said, this custom name shows up on my network after reboot, however Panel still shows the default system name even after closing and reopening Panel.
Another curiosity, assuming the reason the custom system name was accepted by not using any capitals or spaces, the default system name does make use of capital letters, so why can't they be used in a custom system name?