L2tp clients behind NAT break the connection to the server on Mikrotik. Cause?

Question

System administration

We have heterogeneous l2tp clients (vin, mikrot) that cling to the server on mikrot with realnik. Vinh connects second ... then a minute later the micro client falls off. Vinh continues to hold the connection. When Kerio acted as a server ... such turbidity was not observed. What could be the reason?

Answer 1

Staff telepaths on vacation. At least quote the logs from the server and from the client Mikrotik.

Answer 2

Put back Kerio or invite a specialist.

Answer 3

We have heterogeneous l2tp clients (vin, mikrot) that cling to the server on mikrot with realnik. Vin connects second ... then a minute later the micro client falls off. Vinh continues to hold the connection. When Kerio acted as a server ... such turbidity was not observed. What could be the reason?

And the reason is the implementation of l2tp / ipsec by Mikrotik.
They fixed it relatively recently in new firmware. At 6.40 exactly everything works. Before that, people suffered if several machines behind one NAT. Related if in more detail with IKE1. As an option, switch to IKE2.
Discussed here - https://habrahabr.ru/post/327152/#comment_10186576
forum.mikrotik.com/viewtopic.php?t=82980