LoRa WiFi V2.1 devices stop talking after a while

Just got delivery of two ESP32 WiFi LoRa V2.1(868-915) devices. With the factory programmed software they swap packets back and forth for a few minutes, but inevitably stop after a while, generally after a hundred or so packets.
What is going on? I would have thought that devices fresh from production wouldn’t show such an obvious defect? I haven’t even tried to program these myself yet. I’ve seen some posts elsewhere about this as well, but no resolution?
I do have some other LoRa devices nearby, but that shouldn’t matter of course.
Also, if someone can point me at the actual source code the units have when delivered I’d be grateful.
PS Sorry, posted this to the wrong category first time.

There is no retransmission mechanism in the factory test program, which means that once the packet is lost, the nodes will no longer communicate.

OK, thanks Saffer. Not a serious issue then. Good to know.