He’s using his own VPN WG Server.
@ johnc
^It’s not the way I’d do it but I don’t see why it wouldn’t work. I’d set some static DHCP leases beforehand, just to be sure: GL GUI → Clients → Online Clients → $clientName → Action → Modify
Another or option is to use LuCI → Network → DHCP and DNS → Static Leases which will give you the equivalent of → Hostnames (result: iphone.lan). You can install LuCI via GL GUI → System → Advanced Settings. Be warned there’s been a lot of changes since 2005/2006.