how do you open firewall..?

The mqtt broker on droplet works when android mqtt client is used .I am assuming firewall is open.

only when using esp8826 the broker does not connect . which it does on local Raspberry pi mosquito broker
this is apart of my ESP response code
(
Attempting MQTT connection…failed, rc=-4 try again in 5 seconds
Attempting MQTT connection…failed, rc=-4 try again in 5 seconds
Attempting MQTT connection…failed, rc=-4 try again in 5 seconds
Attempting MQTT connection…failed, rc=-4 try again in 5 seconds
Attempting MQTT connection…failed, rc=-4 try again in 5 seconds
Attempting MQTT connection…failed, rc=-4 try )