Connection closed on port 443

Question

I have an Ec2 server with Jenkins docker and git installed on it. The server is running behind. Load balancer with dns configured on route 53  A records as alas to the application load balancer the ALB is listener on 80 redirected to 443 map to a target group registered with my instance ID on port 8080 because Jenkins run on port 8080, when I put the URL of my A record on the browser it open up Jenkins default login page, Jenkins time out while am try to configure to build, the error message read as: connection closed on port 443. Please help am behind schedule to start building. Thanks

Answer

How long does the build take?  
If it is longer than the ALB timeout value, it may be disconnecting the session with the Jenkins server, so how about extending the timeout value?  
https://docs.aws.amazon.com/elasticloadbalancing/latest/application/application-load-balancers.html#connection-idle-timeout

Connection closed on port 443

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