set interfaces dummy dum0 address '203.0.113.1/32'
set vpn ipsec interface 'dum0'
set vpn l2tp remote-access authentication local-users username test password 'test'
set vpn l2tp remote-access authentication mode 'local'
set vpn l2tp remote-access client-ip-pool start '192.168.255.2'
set vpn l2tp remote-access client-ip-pool stop '192.168.255.254'
set vpn l2tp remote-access ipsec-settings authentication mode 'pre-shared-secret'
set vpn l2tp remote-access ipsec-settings authentication pre-shared-secret 'foobar'
set vpn l2tp remote-access outside-address '203.0.113.1'

vyos@r1:~$ sudo netstat -tulpn | grep 1701
vyos@r1:~$ 


vyos@r1:~$ sudo systemctl status accel-ppp@l2tp
● accel-ppp@l2tp.service - Accel-PPP - High performance VPN server application for Linux
     Loaded: loaded (/lib/systemd/system/accel-ppp@.service; disabled; vendor preset: enabled)
     Active: active (running) since Thu 2021-08-12 08:39:54 UTC; 7min ago
   Main PID: 1204 (accel-pppd)
      Tasks: 5 (limit: 546)
     Memory: 2.2M
        CPU: 42ms
     CGroup: /system.slice/system-accel\x2dppp.slice/accel-ppp@l2tp.service
             └─1204 /usr/sbin/accel-pppd -d -p /run/accel-pppd/l2tp.pid -c /run/accel-pppd/l2tp.conf

Aug 12 08:39:54 r1 systemd[1]: Starting Accel-PPP - High performance VPN server application for Linux...
Aug 12 08:39:54 r1 systemd[1]: accel-ppp@l2tp.service: Can't open PID file /run/accel-pppd/l2tp.pid (yet?) after start: Operation not permitted
Aug 12 08:39:54 r1 systemd[1]: Started Accel-PPP - High performance VPN server application for Linux.
Aug 12 08:39:54 r1 accel-l2tp[1204]: l2tp: iprange module disabled, improper IP configuration of PPP interfaces may cause kernel soft lockup
Aug 12 08:39:54 r1 accel-l2tp[1204]: l2tp: impossible to start L2TP server: bind() failed: Cannot assign requested address

set vpn l2tp remote-access outside-address '0.0.0.0'