Wago PFC300 WagoAppSocket UDP Receive not working

Hello,

I have a strange problem with receiving UDP packets on a WAGO PFC300 (FW31).

Current situation:

  • UDP communication between PC (Python) and PFC300 works correctly in both directions.
  • Sending UDP packets from PFC300 to a third-party device also works correctly.
  • The third-party device receives packets from the PLC without any issue.
  • The problem is only with receiving UDP packets from the third-party device on the PFC300.

What I already checked:

  • Packets are visible on the controller via SSH using tcpdump.

  • UDP checksum is OK.

  • Packets arrive on br0 interface.

  • Different UDP ports were tested (4090, 5000, 10000).

  • Separate sockets/tasks were used for Tx and Rx.

  • Tried both:

    • WagoAppSocket library
    • CAA Net Base Services (NBS.UDP_Peer)
  • Same result in all cases: packets are visible in tcpdump, but CODESYS application does not receive them.

Additional notes:

  • EtherCAT is running on X2/br1.
  • UDP communication is on X1/br0 only.
  • Firewall/iptables is empty.
  • Python-generated UDP packets are received correctly by the PLC.
  • Only packets from the third-party device are not delivered to the CODESYS socket layer.

Did anybody experience something similar on PFC300/Linux bridge interfaces?
Any ideas what else could be checked?

Best regards,
Oleksii

solved. device sent pakets with head Ethernet II( its include IP src, dst, MAC src,dst). And dst MAC was wrong. As I understand right Linux core refused these packets.