2x Mikrotik CCR1072 UDP out-of-order issue

RouterOS Forwarding Protocols
1

Hi all,

1st: CCR1072 firmware 6.44.2
2nd: CCR1072 firmware 6.44.3

I have 2 CCR1072 routers in 2 different datacenters, both routers are connected with eachother via a 10GB dedicated link..
Now there are UDP streams going over this link but the packets are one-way out-of-order.

When using iperf (on 2 dedicated debian 9 machines) when going from DC A to B then I get 0% errors and all packets are in order, but when I reverse the test from DC B to A then all packets are out of order which results in corruption of the UDP streams..
All packets are QOS tagged which is working correctly (Using queue tree for the time-critical packets)

Im using a MPLS/VPLS to bridge to 2 networks. Heres the output of iperf of both locations:

2

this normally happen when doing load-balancing between two links and cause udp packet to be out of order
So this might mean there is load-balancing in one direction

3

I just checked, there is no loadbalancer active on that link

4

If someone runs into the same issue, I have found the problem;

On one SFP+ interface flow control was set on auto, after setting flow control on OFF the problem was gone..