Socket leaks

This applies to devices with the u-blox SARA-R410 cellular component used in the XBee 3 Cellular LTE-M Global Smart Modem.

Condition

There are instances where a socket leaks when closing a connection while there is pending RX data. This state is reported whenever the number of leaked sockets causes an inability to create a new connection.

For Transparent and API modes the XBee 3 Cellular LTE-M/NB-IoT returns specific status responses to describe that you need to perform a hard reset to recover the leaked sockets. These statuses are:

Mode	Response
Transparent mode	CI (Protocol/Connection Indication) reports 0x13 Socket leak
API mode	Transmit (TX) Status - 0x89 status 0x32 Resource error (retry operation later)
MicroPython	When attempting to make a connection to a server you receive errno.ENFILE (7023)

Solution

To recover the leaked sockets and make them available again in all modes, you should perform a reset of the cellular component (hard or soft).