My application was working fine but suddenly it saying connection refused

Thanks for reaching out with this issue.

With "Connection Refused" errors, a variety of factors could be the cause. That being said, there are some places to look that will provide some great information which will help you troubleshoot:

If you can provide the output of sudo netstat -plunt the community might be able to provide you with more specific answers. The output from netstat offers details on active TCP connections and the TCP and UDP ports on which a computer is listening.

Additionally, the "Connection Refused" error could indicate firewall issues. The following links have information which will help you review the rules in place, and make adjustments if you need to.

Control Network Traffic with iptables

How to Configure a Firewall with UFW

You can also check your service's error logs with tail -n 20 <path/to/logfile>
To find where your Laravel logs are located, please take a look at Laravel logs.

For more, please refer to this post: How do I check my server's log files

It is also possible that adding the controller impacted your Server Configuration. This link to the Laravel Configuration documentation has a lot of information on setting up the server.

If you have any additional error messages or findings, feel free to share the specifics here and someone will be happy to help!