BG95-M3 server unreachable when idle on NB-IoT

IoT Modules LPWA Module
1

We run our modules as a server. We use M66, M95, EG91 and now we’re trying the BG95.

It’s 80% reliable but not perfect on GSM. On NB-IoT I’ve found it’s fine if we constantly keep it active and it reports csq:31

Then if we let it idle for 20s perhaps(?) the signal strength drops to about 10 and we can’t contact it as a server. It can do a http request the second time we attempt it with it reporting CME: 703 the first time. So it looks like it goes asleep.

However, as far as I can see it is set to stay active:

+QPSMS: 0,“0”,“0”

+CPSMS: 0,“01100000”,“00000000”

I think I’m missing something. Can anyone help?

Thanks

2

After spending more time on this it looks like it is the case that the cell id changes

+CEREG: 5,“E40B”,“6D715”,9,“00000000”,“01100000”

+CEREG: 5,“E40B”,“1D01F”,9,“00000000”,“01100000”

…at which point the server is no longer reachable… unless we de-attach, re-attach and restart the server

at+cgatt=0
+QIURC: “pdpdeact”,1

+CEREG: 0,“00000000”,“01100000”
at+cgatt=1

AT+QIOPEN=1,2,“TCP LISTENER”,“127.0.0.1”,0,80,0

+QIOPEN: 2,0

+QIURC: “incoming”,11,2,“10.65.8.13”,63948

+QIURC: “recv”,11

3

And no this is not the case. It just disappears sometimes even in the same cell.

4

20 seconds is quite common value for RRC inactivity timer, but you state that PSM is disabled. Have you tried to enable +QCSCON messages using AT+QCSCON=1? This way you can see if the module is connected or idle. Or check by yourself by AT+QCSCON?. Maybe you have eDRX enabled? What does AT+CEDRXS? give you?