How to setup L2TP VPN server without IPSec encryption in Linux (Ubuntu)?

Question

VPN

Tell me how to raise (configure) L2TP VPN server without IPSEC encryption in Linux (Ubuntu).
With L2TP VPN with IPSec encryption, I found a lot of instructions, and even ready-made scripts, and even managed to set it up. But I can't find any instructions for L2TP VPN without IPSec.
Conditions: Computer behind a router, port 1701 forwarded both TCP and UDP. OS Ubuntu 18.04.5 LTS (clean, with all the latest updates). You don't need to go online with this VPN.
I installed the L2TP server
apt-get install xl2tpd
and as soon as I didn’t set up the file
vi /etc/xl2tpd/xl2tpd.conf
, the server doesn’t start, and I can’t connect to it.
port = 1701 forwarded in the router
Maybe someone has a L2TP VPN configuration script without IPSec (encryption is simply not needed in this case).
Maybe clients just can't connect without encryption? Somewhere I read that maybe Windows does not just give an unencrypted connection.
But they also write that many routers and the same SoftEther VPN have the ability to disable IPSec encryption, which means that such a connection without encryption still happens to be used and applied.
How to set it up in xl2tpd?
Maybe someone has a configured L2TP VPN without IPSec, you can throw
off
the
configuration
files then? Or forward some other ports (the server is behind the router, the external IP is white)
Thank you!
Added:
changed-changed settings xl2tpd server seems to have started

[email protected]:/home/s# /etc/init.d/xl2tpd restart
[ ok ] Restarting xl2tpd (via systemctl): xl2tpd.service.

But I still can't connect.
Either error 651 then (now) 868 has become

Answer 1

Can you advise any other simple way to combine several computers of different providers into a network. There is one white IP (in one place) Ubuntu server behind the router.
On the router only PPTP and no longer works (blocked by those who are MGTS, MTS ....)