XBee WiFi SB6 UDP Data Rate In Soft-AP Mode Is Very Low For API Mode

I have 2 XBee WiFi SB6 Modules connected and communicating via UDP in API Mode. One module is in Soft-AP Mode and the second is a client to the first. They are successfully associated and communicating. The baud rate is 115200 with 1 stop bit, and CTS / RTS flow control is enabled in the module and on the controller board ( Which is a Raspberry Pi ).

The client is transmitting 0x20 API IPV4 Transmit Request frames to the Soft-AP XBee module.

Everything is working - but the throughput is terrible.

The X-CTU packet generator describes the RF Payload as having a max size of 1400 Bytes.

It seems that if I do anything over 25 bytes in the RF Payload of the 0x20 Frame, the Receive XBee receives no bytes.
It seems that if I do anything under 25 bytes in the RF Payload of the 0x20 Frame, the Receive XBee gets all intended bytes.

I’ve tried 100,200,300,1400 and other RF Packet sizes, but none of them are received.

What gives? Flow control and smaller packets work with my setup, but simply nothing greater than ~15 bytes?

What in the world could I be doing wrong? Thanks!

Check the API frames to see if they are valid. I suspect you are using a version of the XCTUNG software which has issues with the WIFI API frames.