Config for Deutsche Telekom VDSL2 socket with VLAN7 tagging:
/etc/config/network:
config interface 'WAN'
option proto 'pppoe'
option ipv6 'auto'
option username '<Anschlusskennung><Zugangsnummer>#0001@t-online.de'
option password '<password>'
option ifname 'eth1.7'
Run once: /etc/init.d/sfpswitch enable; /etc/init.d/sfpswitch restart && /etc/init.d/network reload && echo 'Success' || echo 'Failed'