No connection between Openhab and working MQTT broker (timed out) [SOLVED]

[DutchMurk]

I gradually started to build my first system. After getting experience with the serial gateway, I shifted to the th ethernet Gateway and now want to setup the MQTT gateway. Everything is functioning,** I can see the MQTT updates in MQTTlens (temperature readout)** but by no means I can connect my Openhab system to the MQTT broker on the Arduino UNO. I get a timeout connection error all the time:

21:14:10.253 ERROR o.o.i.t.mqtt.MqttService[:114] - Error starting broker connection
org.eclipse.paho.client.mqttv3.MqttException: Unable to connect to server
at org.eclipse.paho.client.mqttv3.internal.TCPNetworkModule.start(TCPNetworkModule.java:75)
at org.eclipse.paho.client.mqttv3.internal.ClientComms$ConnectBG.run(ClientComms.java:538)
at java.lang.Thread.run(Unknown Source)
Caused by: java.net.ConnectException: Connection timed out: connect
at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at org.eclipse.paho.client.mqttv3.internal.TCPNetworkModule.start(TCPNetworkModule.java:66)
at org.eclipse.paho.client.mqttv3.internal.ClientComms$ConnectBG.run(ClientComms.java:538)
at java.lang.Thread.run(Unknown Source)

I have googled for any solution and I checked double-checked all my settings but I am out of ideas, specially because I can connect/receive messages from the MQTT broker to my android phone and my desktop. Anyone any suggestions where to look ?

[yancym]

Is your MQTT binding set up in OpenHAB.cfg? What are the settings?

[DutchMurk]

The set-up in Openhab was working because I was able to connect to another MQTT server on my Synology. I just changed the code a little by also defining the DNS server and subnet mask

#define TCP_PORT 1883 // Set your MQTT Broker Listening port.
IPAddress TCP_IP ( 192, 168, 0, 9 ); // Configure your static ip-address here
byte gateway[] = { 182, 168, 0, 1 };
byte subnet[] = { 255, 255, 255, 0 };
byte TCP_MAC[] = { 0x02, 0xDE, 0xAD, 0x00, 0x00, 0x42 }; // Mac-address - You should change this! see note *2 above!

and

void setup()
{
Ethernet.begin(TCP_MAC, TCP_IP, gateway, subnet);

and it seems and I can connect now during the last two restarts (but I also powered-off my netwerk switch in between). Let's see how it will last.....

[DutchMurk]

My set-up is stable now for a couple of days, even with reboots of MQTT server and my network switch

[Shedrick Bell]

Did you find a fix? I'm having the same problem

[DutchMurk]

My fix was listed above. restarting the routers and defining the static IP