Connection time out after installing firewalld

Question

While configuring a Ubuntu 22 server on a AWS g4dn instance, I tried to check the list of firewall through this command in the git bash terminal.
[firewall-cmd --list-all]
I was told by the terminal to install the firewalld using the following command.
[sudo apt install firewalld] 
However, installation was interrupted with the message below.
[client_loop: send disconnect: Connection reset by peer]
Once I closed the terminal to restart, my ssh connection gets timeout error as the following.
Terminal Input: [ssh -i KeyPair ubuntu@example.us-east-2.compute.amazonaws.com]
Terminal Output: [ssh: connect to host example.us-east-2.compute.amazonaws.com port 22: Connection timed out].

I have checked the Security group and confirmed that TCP port 22 is still available. It seems that the newly installed firewalld is causing the problem.
How can I resolve this issue?

Accepted Answer

1. Use EC2 Instance terminal to connect to the server. [Set up the configuration based on the direction given from AWS console]
2. Once logging in with the user account, switch to root user. [Sudo bash]
3. Disable firewalld with [systemctl disable firewalld]
4. Add 22/tcp to the UFW [sudo ufw allow 22/tcp]

Connection time out after installing firewalld

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