Interfaces renaming

WAN

nano /etc/systemd/network/10-wan.link

[Match]
MACAddress=xx:xx:xx:xx:xx:xx

[Link]
Name=wan

where xx:xx:xx:xx:xx:xx correspond to the MAC addr of WAN interface.

LAN

nano /etc/systemd/network/10-lan.link

[Match]
MACAddress=xx:xx:xx:xx:xx:xx

[Link]
Name=lan

where xx:xx:xx:xx:xx:xx correspond to the MAC addr of LAN interface.