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I've been able to use the browser-based SSH client without any issues until today. Now, I'm getting the following error each time I try to connect. I've tried restarting, stopping/starting, and removing/adding back the static IP.

CONNECTION ERROR An error occurred and we were unable to connect or stay connected to your instance. If this instance has just started up, try again in a minute or two.

Here is a screenshot:

enter image description here

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  • Are you using DHCP on the client side that might have changed the address of your computer? You might need to update the address allowed to connect to SSH through the security group. Jul 31 '17 at 1:47
  • No, not using DHCP or anything different. It's the same case for multiple computers I've tried. For Lightsail, there's no configuration like that; it just works out of the box when you launch the browser-based client while logged in. Jul 31 '17 at 12:45
  • "This question does not show any research effort; it is unclear or not useful" This question shows the research done and is useful to anyone else who has this issue. Jul 31 '17 at 12:46
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The issue was I enabled the ufw firewall on Ubuntu and closed my SSH session. Naturally, I was unable to SSH back in on port 22 since only ports 80 and 443 were allowed at that point.

For Lightsail, I don't think there's a way around it, unless a snapshot from one instance can be loaded onto another instance.

For AWS, you can unmount and put the volume on a new instance: https://forums.aws.amazon.com/thread.jspa?threadID=112384

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  • 2
    I locked myself out the same way. I created the snapshot, created a new instance from that snapshot but ran with (sudo ufw allow ssh) in launch script which fixed the issue
    – SenG
    Oct 30 '18 at 14:18
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Found a solution from the AWS forums that encountered the same problem.

There seems to be an issue that happens with Lightsail setups wherein the web-based SSH service stops working properly for some reason. The advise was to create a snapshot of the Lightsail instance to preserve the current data then create a new instance that installs an updated SSH server using user-data similar to the following:

#!/bin/bash sudo apt-get remove openssh-client openssh-server sudo apt-get install openssh-client openssh-server

It says that web-based SSH might not be possible after since they seem to be using a special SSH configuration for it. You will need to SSH directly to the server using a SSH client.

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  • Does Lightsail allow applying a snapshot from one instance to another instance? Jul 31 '17 at 17:57
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Experienced same issue after I enabled ufw firewall on ubuntu 20.04 but had Installed webmin before this issue. So I used the webmin console to enable ssh via port 22 on the ufw.

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I've seen this happen multiple times and it seems caused by incomplete setup of the server stack due to exhaustion of RAM memory... I don't know why this happens more on AWS than other clouds (even when I setup the exact same server stack).

Try to use a VM with at least 2GB memory and reinstall fresh.

Also I'm not 100% sure but I think port 22 is required for the AWS web-based Console to function regardless of changes you make to sshd_config... and keep in mind that the root user is disabled by default on AWS servers, even in Console mode, so using sudo is required.

On other clouds if there's any issues I can always use the Console to login as root and fix settings and reboot the server but this isn't supported on Amazon, so I use the default port 22 for SSH when using Amazon cloud servers. Also be sure you enable access to that port in both the Networking tab of the machine (AWS UI) and in any firewall too like UFW Firewall.

Besides all this, the Console has had general instability in the past as per @Carlo answer. Again, all of these challenges seem unique to Amazon...

I recommend using other clouds whenever possible lol.

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  1. To fix it, add following 2 lines to /etc/ssh/sshd_config
TrustedUserCAKeys /etc/ssh/lightsail_instance_ca.pub

CASignatureAlgorithms +ssh-rsa
  1. Restart
/etc/init.d/ssh restart

Problem Log in failed. If this instance has just started up, try again in a minute or two.

CLIENT_UNAUTHORIZED [769]

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