Is Xbee WiFi S6B compatible with Xbee WiFi S6 for receiving I/O sampling?

I’m sending I/O samples from Xbee WiFi S6 to Xbee WiFi S6B. S6B is configured in API mode, however S6B is not receiving the I/O samples. If I send serial data from S6 to S6B, data is received correctly in an API frame, but I/O sampling is not. I know samples are sent from Xbee S6 as if I use an UDP monitor in my laptop the message is received.

If I send I/O samples from S6B to S6, I/O samples are received either in API and transparent mode also, however after some time (nor fixed) S6 stops receiving I/O samples from S6B.

As far as I am aware they are.