Xbee S6B Intermittent Operation

I am currently attempting to use a XBee WIFI S6B, running Firmware Version 2026, to log analog sensor data to Device cloud. To save battery power, the module is set to cyclic sleep (5 mins asleep, 120 seconds awake). The long duration of the awake period is based on the release notes for 2026 which indicates that upon wakeup, for nodes associated with a WPA2 access point, it takes around 50 seconds to transmit a TCP packet - plus a buffer.
The system seems to work well for an hour or two and then stops logging data. As it is still sitting in the test board, connected to XCTU, I can change a awake period, rewrite and the problem disappears, albeit temporarily.
Possibly related to the problem - I do not understand the new sleep options (SO) introduced in 2026 and what should actually be entered on XCTU to force dissociation from AP on deep sleep.
Any advice??

To add further detail to the issue above and to start the process of elimination. On power supply - I have subsequently switched the Xbee WIFI S6B module from a USB powered board to a battery powered board with the same result. On WIFI access point, I then switched the Wifi access point from a ethernet connected solution to a cellular modem, with the same result. The point of ceasing data logging over the last four trial runs is actually just over 30mins - consistently on both carriers and wifi access points. Still looking for any advice?

What you need to do is to set the bit mask on the SO command so that bit 6 is Enabled and bit 9 is disabled (0x40).

Thanks mvut,
Following up, when I switched SO to 0x40, I noted that the sleep time was limited to around 120 seconds and was unable to be changed despite varying the SP time to 300,000 ms, 600,000ms and 900,000ms. Any advice on how this can be extended, or is this set in order to stay associated with AP?