from `linux-6.6.108:net/ipv6/addrconf.c`
We can "NOT" use IPv6 `interface tokens` on e.g. WireGuard interfaces. The Linux Kernel
internally will reject this b/c the WireGuard interface itself is not an ARP-linke interface, but IPv6 has no ARP!
```
static int inet6_set_iftoken(struct inet6_dev *idev, struct in6_addr *token,
struct netlink_ext_ack *extack)
{
...
if (dev->flags & IFF_NOARP) {
NL_SET_ERR_MSG_MOD(extack,
"Device does not do neighbour discovery");
return -EINVAL;
}
```