I Can't Connect to my MQTT server via arduino
This is the problem:

mosquitto 10436       mosquitto    4u  IPv4   46043      0t0  TCP
127.0.0.1:1883 (LISTEN)

Your MQTT server is listening only on port 127.0.0.1.  That will accept local incoming connections only but nothing from another IP address.
The IP 127.0.0.1 is the LOCAL ONLY IP address.  You need to reconfigure your MQTT server to listen on either IP 0.0.0.0 or whatever that server's actual IP address is.
Check your mosquitto.conf file and look for the line that begins with &quot;bind_address&quot;:
listener 1883 localhost

change this to:
listener 1883 0.0.0.0

and restart your MQTT server.