The system thread of Device-OS can acquire a lock around the cellular AT interface. By attempting a
SINGLE_THREADED_BLOCK you are running an extremely high risk of deadlocking the system. Connection outages are some of the times that Device-OS is most likely to be communicating with the modem and holding the lock. A deadlock will prevent all FreeRTOS context switching which can also prevent the software application watchdog from triggering.
SINGLE_THREADED_BLOCK is very dangerous and should not be used without careful consideration. Accessing any resource (cellular, wifi, logging, SPI/I2C/UART, dynamic memory, etc) from within such a block can result in deadlocks.
I would also be careful around manual connection management. May interfere with normal Device-OS recovery and cause degenerate connection issues.