Packet loss when using ipsec on the mmips platform

RouterOS General
1

Hello.

I have a problem with packet loss when using Site-To-Site IPSEC VPN on the MMIPS platform with RouterOS version 6.48.10 (long-term).
Connection diagram: PC1 - network - MikroTik hEX - internet - Cisco ASA - network - PC2
All packets from PC2 come to PC1.
I checked the transmission of ICMP packets from PC1 using ping, flood ping - all packets reach the destination. UDP packets are also fine. Perhaps there were not enough packets.
When I start sending TCP packets from PC1, about half of the packets reach their destination.
Very interesting: when I turn on Packet Sniffer on MikroTik hEX, the destinations reach all 100% of the packets.
Can someone help me with the problem?

2

Make sure you do not fasttrack the inner-tunnel traffic. Perhaps just try disabling all fasttrack rules first and see if it helps.

3

Thanks. The range of addresses behind the tunnel was included in the fasttrack rule.
It works now.