Blocking fragmented packets?

RouterOS General
1

Hi!
I have my PC and external dj controller connected via MikroTik RB-951-2HnD to the same LAN. They should communicate through rekordbox software, but it looks like mikrotik somehow blocks some traffic between PC and controller. Look what happens when PC and controller are connected directly with LAN cable:

As you can see, PC sends few packets, then acquire confirmation from controller through NFS, and then it sends next part of data starting at different offset. And what happens when I connect them to the same network on mikrotik?

1.0.0.20 is PC, 1.0.0.12 is controller. After first set of packets, controller replies with “retransmission” what means, that it didn’t receive this set of data. So next set of data is starting from offset = 0. And over and over again… Also there is some additional traffic on UDP just between two data sets. Just wondering what it can be and if it can affect connection somehow.

My mikrotik is configured as follows:
eth1 - WAN port
eth2 - eth5 are in switch mode, where eth2 is master.
There are no firewall rules that drop any packet at all.

Any thoughts?
If you want to see content of any packet on the screen, just let me know. I saved dump from wireshark.

Thank you in advance!

2

Did you mean to use 10.0.0.0/8 for your network? 1.0.0.20 is publicly routable, you shouldn’t be using it on your internal network. Most likely it is being blocked by a firewall on the endpoint as it isn’t considered a private network.

3

No, 1.0.0.0/24 is set purposely - just because I can. I have in mind that this address pool doesn’t fit standards. I also had a suspicion that this kind of address pool may cause problem, but this is the first occurence here. Anyway, I have to change network address to check if it work.

4

I’ve changed network to 192.168.2.0/24 and the same thing happen.