Cannot connect to Amazon Linux AMI EC2 instance - amazon-ec2

I have been connecting just fine with my ec2 instance ad suddenly today when I tried connecting i get "connection refused". My security setting for ssh is set to all, and I have also set it to my specific IP address for good measure. Please can someone advise? I have also tried rebooting the system from the console.

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EC2 Instance Connect (browser-based SSH connection) doesn't work

Trying to connect Amazon AWS EC2 instance fails.
Platform: Amazon Linux
Connection method: EC2 Instance Connect (browser-based SSH connection)
Error: There was a problem setting up the instance connection
Log in failed.
If this instance has just started up, try again in a minute or two.
Note: I am able to connect via Putty / SSH Client. But same instance can't connect via browser.
When checked network logs in browser's developer tool, see a Status Code: 400 Bad Request for following URL:
https://ec2-instance-connect.us-east-2.managed-ssh.aws.a2z.com/ls/api/tokens
Has anyone ever successfully connected to Amazon Linux EC2 instance from browser.
To test, I just did the following:
Launched an Amazon Linux 2 EC2 instance with the default security group
Clicked "Connect" in the EC2 management console
Selected "EC2 Instance Connect"
Clicked "Connect"
A new browser tab opened and a few seconds later I had a working SSH connection.
I then tried it again with an Amazon Linux (not Amazon Linux 2) instance and got the error:
There was a problem setting up the instance connection
Log in failed. If this instance has just started up, try again in a minute or two.
This is because the EC2 Instance Connect client is only pre-installed on Amazon Linux 2 and Ubuntu 16.04 or later.
You can use EC2 Instance Connect with your ssh client. In case you really need the browse-based connection, your security group must have a rule allowing SSH connections (port 22) from 0.0.0.0/0. Not much secure in my point of view...
This is for AWS Lightsail, I could not use browser to connect via SSS, instead I was able to connect via SSH using macOS terminal. I was able to login via SSH by appending my public key id_rsa.pub contents to the remote authorized_keys file, I used SFTP (Filezilla) to update authorized_keys file. For SFTP connection I downloaded ssh key from Accounts page.

Amazon EC2 instance not able to access via ssh

I am not able to access my amazon ec2 instance via ssh using putty and git bash. The webpage that it is linked to is working and I am able to connect to it.
The ec2 instance is a ubuntu machine. All the security rules are set properly. I also found that the instance is not listening on port 22. Maybe that is the problem but then how can I access it without using Putty?
Any and all help will be appreciated.....

Changes to iptable blocked all the ports, hence unable to connect to this Amazon EC2 instance through putty

Yesterday I was working on blocking of access to Redis server from out side doing by doing some changes to "iptable" file, unfortunately it blocked all the port which includes port 80 and 22 also, Hence I was unable to connect to EC2 instance from putty. Will you tell me how to resolve this issue.
You will have to do something like this: https://aws.amazon.com/articles/5213606968661598
I hope you are using EBS and not ephemeral storage. You know you could have used EC2 Security Groups instead of iptables, and then you could have easily fixed your mistake.

I suddenly cannot connect to my EC2 instance. Why? How can I mitigate this?

I had a running instance, and then I became unable to connect to it via http(80) and ssh(22). I tried to reboot the instance, but nothing went up. This has happened to me twice in the past month.
Why does it happen? Can I do anything to fix and/or prevent it from happening?
If I launch a new instance in same region, and it works.
Things to check when trying to connect to an Amazon EC2 instance:
Security Group: Make sure the security group allows inbound access on the desired ports (eg 80, 22) for the appropriate IP address range (eg 0.0.0.0/0). This solves the majority of problems.
Public IP Address: Check that you're using the correct Public IP address for the instance. If the instance is stopped and started, it might receive a new Public IP address (depending on how it has been configured).
VPC Configuration: Accessing an EC2 instance that is launched inside a Virtual Private Cloud (VPC) requires:
An Internet Gateway
A routing table connecting the subnet to the Internet Gateway
NACLs (Network ACLS) that permit through-traffic
If you are able to launch and connect to another instance in the same subnet, then the VPC configuration would appear to be correct.
The other thing to check would be the actual configuration of the operating system on the instance itself. Some software may be affecting the configuration so that the web server / ssh daemon is not working correctly. Of course, that is hard to determine without connecting to the instance.
If you are launching from a standard Amazon Linux AMI, ssh would work correctly anytime. The web server (port 80) would require installation and configuration of software on the instance, which is your responsibility to maintain.

I cannot acess to the website host on Amazon EC2 instance even I think the configuration is right

I have a free Amazon EC2 instance. And I installed Apache web server on it. I have the DNS record for my domain point to the ip for the EC2 instance. I can not access to my website. Then I looked up and allow the http inbound. But I still failed to access my web? What might be the reason. Anybody gives me a clue?
Go to the AWS management console and look at the Security Group the instance is in. Then make sure you have the port open that you are trying to connect to (most likely 80). To open it to the world set the ip range to 0.0.0.0/0 and to open it to a specific ip (like only your house) set it to xxx.xxx.xxx.xxx/32.
That is almost always the reason people have problems connecting when they are new to AWS. I wrote this post, which should help get you setup.

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