WIZ550S2E TCP not working on corporate network. loses first 16 bytes of data.

Hi, I am new to the forum, but have been working with the WIZ550S2E with version 1.4.0 firmware for a few months.
I am using the module in 2 application in different modes, both use DHCP.
Mode #1 UDP in Data Mode
Mode #2 TCP in Command mode, using AT+NSEND

On small networks both modes work fine. On a corporate (domain) network with a Windows DHCP server Mode #1 works fine but in Mode #2 I am losing the 1st 16 bytes of the data packet. This Wireshark trace shows the problem:

This trace shows what should be in the data block:

Does anyone have any suggestions as to what is causing this data loss?

Thanks

John

A follow on to this earlier post. Command mode UDP messages have the same problem. OK in data mode, but when sending on a corporate network we again lose the first 16 or 17 bytes in UDP using AT+NSEND

any suggestions?

thanks

John

Hi John,

Could you share the ‘*.pacp’ file that captures the problem?

Hi Austin,

I have attached the filtered file (tcp.port==4437) to keep it small!

Hope this is of use

Best regards

John

John Comfort

JCA Systems Ltd

(Attachment EC4Plus_LAN_BATH6 filtered.pcapng is missing)

Hi Austin,

I have attached the filtered file (tcp.port==4437) to keep it small!

Hope this is of use

Best regards

John

John Comfort

JCA Systems Ltd

EC4Plus_LAN_BATH6 filtered.zip (15.5 KB)