What could be the problem with VPN crashes?

Question

VPN

On Mikrotik, the standard vpn L2TP / IPSEC is raised.
Users normally connect, but after a while (5-30 minutes) they are thrown out.
Log writes

Google does not really say anything ... Maybe someone came across?
Settings screen (everything else is default)

Answer 1

As it turned out later, the problem was caused by a limitation of the IPSec protocol.
From one "white" IP address there can be only one connection.
The user was thrown out as soon as someone else connected to the VPN.
The solution was to switch to using SSTP with a self-signed certificate.