Can't reconnect to MQTTSN gateway

Question

I have been running a mqttsn client publisher/subscriber project (based on the example) successfully for some months. I have added a mosquitto broker to the raspberry pi border router. Each thread node publishes data every 10 seconds. 
 SDK: nRF5_SDK_for_Thread_and Zigbee_2.0.0 
 RaspPi image: RaspPi_Thread_Border_Router_Demo_2.0.0-1.alpha 
 I turned both the raspberry pi and thread node on at the same time several weeks ago. Today, the connection to the broker was lost and cannot be regained. A second thread node with debugger attached shows that the gateway is found, but the connection ( mqttsn_client_connect(&m_client, &m_gateway_addr, m_gateway_id, &m_connect_opt); ) times out repeatedly. I am assuming the Thread network connection is ok, since the gateway was found. 
 My PC remains connected to the broker on the raspberry pi, but is not receiving any messages. I have repeatedly restarted the node attached to the debugger, and it continues to timeout on the mqtt gateway connection. 
 This error occurs infrequently (only after running continuously for several weeks). What can I check on the raspberry pi to diagnose the problem? 
 Thanks, 
 Mary

Mary · Accepted Answer

I was able to download and compile the latest MQTTSN-Gateway. This solved my problem. I was able to have a node reboot every 10 seconds and successfully reconnect for several hours. 
 Instructions for compiling the MQTTSN-Gateway are here . 
 Here's what I did: 
 Before compiling on the RaspberryPi, first install ssl-dev. This adds header files, etc so you can compile OpenSSL dependent code.. 
 $ sudo apt-get update
$ sudo apt-get install libssl-dev
 
 Create a working directory. I used /home/pi/Projects. 
 Next, build the gateway: $ cd ~
$ mkdir Projects
$ cd Projects
$ git clone -b experiment https://github.com/eclipse/paho.mqtt-sn.embedded-c 
$ cd paho.mqtt-sn.embedded-c/MQTTSNGateway 
$ make SENSORNET=udp6 
$ make install INSTALL_DIR=/home/pi/Projects/MQTTSNGateway_v1.3.1 CONFIG_DIR=/home/pi/Projects/MQTTSNGateway_v1.3.1 
$ make clean 
 
 Stop the currently running gateway: 
 $ sudo systemctl stop paho-mqttsn-gateway.service 
 Edit the service file: 
 $ sudo nano /etc/systemd/system/paho-mqttsn-gateway.service 
 Change the ExecStart line to explicitly specify the configuration file: 
 ExecStart=/usr/sbin/MQTT-SNGateway -f /etc/paho-mqtt-sn-gateway.conf 
 Copy the predefinedTopics.conf file from the CONFIG_DIR to /etc or add a new file for predefined topics and edit as needed. 
 $ sudo nano /etc/predefinedTopic.conf 
 Make a backup of the original executable and copy the new one to /usr/sbin: $ sudo cp /usr/sbin/MQTT-SNGateway /usr/sbin/MQTT-SNGateway_v1.0.1

$ sudo cp /home/pi/Projects/MQTTSNGateway_v1.3.1/MQTT-SNGateway /usr/sbin/MQTT-SNGateway

$ make clean
 
 Restart the gateway: 
 $ sudo systemctl start paho-mqttsn-gateway.service 
 Viewing the systemd log will show the gateway activity. 
 $ journalctl -ef

Mary · Answer

I stopped and restarted mosquitto: 
 /etc/init.d/mosquitto stop 
 /etc/init.d/mosquitto start 
 
 then restarted the gateway: 
 sudo /usr/sbin/MQTT-SNGateway -f paho-mqtt-sn-gateway.conf & 
 and it ran. 
 Message publishing is now restored, (but all the messages from the gateway are printing to my raspberry pi console.)

Can't reconnect to MQTTSN gateway

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