edgemax L2tP

configure

set firewall name WAN_LOCAL rule 100 action accept
set firewall name WAN_LOCAL rule 100 description 'Allow IKE for Remote VPN Server'
set firewall name WAN_LOCAL rule 100 destination port 500
set firewall name WAN_LOCAL rule 100 log enable
set firewall name WAN_LOCAL rule 100 protocol udp
set firewall name WAN_LOCAL rule 110 action accept
set firewall name WAN_LOCAL rule 110 description 'Allow L2TP for Remote VPN Server'
set firewall name WAN_LOCAL rule 110 destination port 1701
set firewall name WAN_LOCAL rule 110 log enable
set firewall name WAN_LOCAL rule 110 protocol udp
set firewall name WAN_LOCAL rule 120 action accept
set firewall name WAN_LOCAL rule 120 description 'Allow ESP for Remote VPN Server'
set firewall name WAN_LOCAL rule 120 log enable
set firewall name WAN_LOCAL rule 120 protocol esp
set firewall name WAN_LOCAL rule 130 action accept
set firewall name WAN_LOCAL rule 130 description 'Allow Nat-T for Remote VPN Server'
set firewall name WAN_LOCAL rule 130 destination port 4500
set firewall name WAN_LOCAL rule 130 log enable
set firewall name WAN_LOCAL rule 130 protocol udp

set vpn ipsec ipsec-interfaces interface eth0 # your WAN interface
set vpn ipsec auto-firewall-nat-exclude enable
set vpn ipsec nat-networks allowed-network 0.0.0.0/0 # check that's OK before you set it
set vpn l2tp remote-access authentication mode local
set vpn l2tp remote-access authentication local-users username <user> password <password>
set vpn l2tp remote-access client-ip-pool start <starting IP>
set vpn l2tp remote-access client-ip-pool stop <end IP>
set vpn l2tp remote-access dns-servers server-1 <DNS server IP>
set vpn l2tp remote-access ipsec-settings authentication mode pre-shared-secret
set vpn l2tp remote-access ipsec-settings authentication pre-shared-secret <secret>
set vpn l2tp remote-access ipsec-settings ike-lifetime 3600
set vpn l2tp remote-access outside-address <WAN IP address>
set vpn l2tp remote-access outside-nexthop <next hop after the WAN IP, at your ISP>
set vpn l2tp remote-access mtu 1492
commit
save
exit

Credits als go to:
https://gist.github.com/rys/868808662d041a11a4d4
http://vbrainstorm.com/setup-an-l2tpipsec-vpn-on-your-ubitquiti-edgerouter/