pfSense

Hi,

After upgrading from pfsense CE 2.5 to 2.7 some UDP packets started unexpectedly to loss on GRE interface.

Let me show the path of sending packets -
computer in vlan_A sends packet from port 3305 -> net_vlan_A -> pfsense site A -> GRE -> pfsense site B -> net_vlan_B -> computer in vlan_B to port 3310
So I can see my packets on pfsense vlan_A interface via tcpdump, but they dissapear on GRE.

Take a look on screenshots I attached to this issue.
On first screenshot is shown sending different packets via netcat, on the second which packets I can see on GRE.

Moreover, if i change source or destination ports, traffic goes well.

I don't have any rules for certain ports 3305 and etc.

The issue is really hard to catch, sometimes traffic goes right, sometimes is not.

Can I ask for your help to investigate this issue? If you need more information please let me know.