problem with sending speed of Low Latency 40G Ethernet Intel FPGA IP

[GoodmanKIWI]

Hi everyone:
I'm using Low Latency 40G Ethernet Intel FPGA IP.
I made a demo to receive data from another my FPGA device(10AX027H4F34I3SG).

The demo is about sending one frame data,one packet has 7680 bytes,one frame has 4320 packets. Although I have chosen average interpacket with 12.If I don't add another time interval,the packets received by computer will appear dropped. Even I add another time interval.I can't always received all packets I have sent.Every one thousand packets,There appears one packet dropped.

I think perhaps I have missed some setting or initial setting. 

The ip setting is here.
Thank you in advance.