How to change Link Local on WAN?

[GennP]

How to change Link Local on WAN?
Now it take from first interface (like vmx0)
Trying to put MAC in Interface-WAN but wont connect after this.

vmx0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
	description: LAN3
	options=e000bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,RXCSUM_IPV6,TXCSUM_IPV6>
	ether c4:09:af:e4:10:03
	inet6 fe80::c609:afff:fee4:1003%vmx0 prefixlen 64 scopeid 0x1
	inet6 2001:****:****:****::1 prefixlen 64
	inet 192.168.3.1 netmask 0xffffff00 broadcast 192.168.3.255
	media: Ethernet autoselect
	status: active
	nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>

pppoe0: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> metric 0 mtu 1492
	description: WAN
	inet *.*.*.* --> *.*.*.* netmask 0xffffffff
	inet6 fe80::c609:afff:fee4:1003%pppoe0 prefixlen 64 scopeid 0xa
	inet6 2a01:***:**:****:c609:afff:fee4:1003 prefixlen 64 autoconf
	nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>