I have a nRF9151 currently set up to observe a CoAP resource on my server. The initial GET request works, and if I respond with new updates from the server (within a few seconds) everything works fine. If I wait more than ~10 seconds however, the device goes into RRC idle, and then the device becomes forever unreachable (subsequent messages from my server result in a context canceled error, which I assume is due to it no longer being able to reach the device)
I have eDRX and PSM both off. No DTLS. My CoAP thread is just a while(1) loop with nrf_recv() waiting for data in blocking mode.
I've tried messing with various socket options such as NRF_SO_KEEPOPEN, but I get the same behaviour.
I logged out the modem activity but there's nothing unusual there. Interestingly if I'm fast enough, even after RRC idle I can receive new messages, but if I wait too much longer after, then it won't ever arrive. The last RRC idle in the log is where this happened. I waited a few more seconds and got nothing after that.
My question is, what could be causing the connection to get dropped? Is there some way I could log whatever causes this?
[00:00:46.052,978] <inf> nrf_modem: recv() fd 0x0, buf 0x2001f2c0, len 1072, flags 0x0 (blocking) [00:00:47.831,542] <inf> nrf_modem: RPC_IP_RECVFROM_NTF fd 0x0 (28 bytes) [00:00:47.831,909] <dbg> nrf_modem: Incoming pkt, data 0x20018ba0, len 28 [00:00:47.832,336] <dbg> nrf_modem: Freeing pkt 0x2001cf6c, data 0x20018ba0, sockaddr 0x2001cf84 Request: Received 11 bytes of payload data [00:00:47.833,007] <inf> nrf_modem: recv() fd 0x0, buf 0x2001f2c0, len 1072, flags 0x0 (blocking) [00:00:50.129,119] <dbg> nrf_modem: +CSCON: 0 Modem: RRC idle [00:00:52.730,926] <dbg> nrf_modem: +CSCON: 1 Modem: RRC connected [00:00:52.876,800] <inf> nrf_modem: RPC_IP_RECVFROM_NTF fd 0x0 (28 bytes) [00:00:52.877,197] <dbg> nrf_modem: Incoming pkt, data 0x20018ba0, len 28 [00:00:52.877,593] <dbg> nrf_modem: Freeing pkt 0x2001cf6c, data 0x20018ba0, sockaddr 0x2001cf84 Request: Received 11 bytes of payload data [00:00:52.878,295] <inf> nrf_modem: recv() fd 0x0, buf 0x2001f2c0, len 1072, flags 0x0 (blocking) [00:00:54.005,798] <dbg> nrf_modem: rpc_softsim_event_handler cmd: 3, req_id: 50, data_len: 7 [00:00:54.019,287] <dbg> nrf_modem: nrf_modem_softsim_res cmd: 3, req_id: 50, data_len: 52 [00:00:57.009,338] <dbg> nrf_modem: +CSCON: 0 Modem: RRC idle [00:00:57.851,104] <dbg> nrf_modem: +CSCON: 1 Modem: RRC connected [00:00:58.009,918] <inf> nrf_modem: RPC_IP_RECVFROM_NTF fd 0x0 (28 bytes) [00:00:58.010,314] <dbg> nrf_modem: Incoming pkt, data 0x20018ba0, len 28 [00:00:58.010,711] <dbg> nrf_modem: Freeing pkt 0x2001cf6c, data 0x20018ba0, sockaddr 0x2001cf84 Request: Received 11 bytes of payload data [00:00:58.011,413] <inf> nrf_modem: recv() fd 0x0, buf 0x2001f2c0, len 1072, flags 0x0 (blocking) [00:01:00.311,920] <inf> nrf_modem: RPC_IP_RECVFROM_NTF fd 0x0 (28 bytes) [00:01:00.312,316] <dbg> nrf_modem: Incoming pkt, data 0x20018ba0, len 28 [00:01:00.312,744] <dbg> nrf_modem: Freeing pkt 0x2001cf6c, data 0x20018ba0, sockaddr 0x2001cf84 Request: Received 11 bytes of payload data [00:01:00.313,415] <inf> nrf_modem: recv() fd 0x0, buf 0x2001f2c0, len 1072, flags 0x0 (blocking) [00:01:01.911,987] <inf> nrf_modem: RPC_IP_RECVFROM_NTF fd 0x0 (28 bytes) [00:01:01.912,353] <dbg> nrf_modem: Incoming pkt, data 0x20018ba0, len 28 [00:01:01.912,780] <dbg> nrf_modem: Freeing pkt 0x2001cf6c, data 0x20018ba0, sockaddr 0x2001cf84 Request: Received 11 bytes of payload data [00:01:01.913,452] <inf> nrf_modem: recv() fd 0x0, buf 0x2001f2c0, len 1072, flags 0x0 (blocking) [00:01:04.209,564] <dbg> nrf_modem: +CSCON: 0 Modem: RRC idle
