RAK8212/BG96 tcp close socket anomaly

It might help to give a bit of the dump before [BG96] AT+QISEND response undefined?

What's happening is the send function isn't getting the response it wanted with the given time period (you didn't lower the timeouts in your version did you?). Although as you say there's a SEND OK I think what comes before it is more interesting.

My guess is that the BG96 may actually output > without \r\n sometimes (even though it appears to normally) - which means > never gets sent on to the handler.

I assumed wrong on a change for ESP8266 extremely recently, and had to make this change: https://github.com/espruino/EspruinoDocs­/commit/7b4b448647bdf24fe22dadd15b135227­e2cc8ad0#diff-465a45343fb61c597d45aa2f89­be369b

It's possible that if you make a similar one, it'll work.