title: Can't connect to Amazon EC2 instance with PuTTY
body: <p>I have been able to connect to <code>Amazon Web Services EC2</code> with the free tier and run <code>R</code> programs with it.  Now I am trying to use an instance with a Spot Request.  The instance is created and running and both Status Checks are okay.  However, <code>PuTTY</code> will not connect.  <code>PuTTY</code> will still connect to the free instance using the same steps and the same <code>key pair</code>.</p>
  
  <p>Can anyone suggest what I am doing incorrectly?  Here are the details of the two instances if this information might be helpful.  I am hiding portions of the <code>Instance IDs</code>, the <code>IPs</code>, the <code>Owner ID</code> and the <code>Reservations</code> and have provided a fake <code>key pair</code> name.</p>
  
  <p>Here are Description details of the Spot instance I cannot connect to with <code>PuTTY</code>:</p>
  
  <pre><code>Instance ID: i-XXXXXa30498b1b9ca
  Public DNS (IPv4): ec2-XX-XXX-XXX-XXX.us-east-2.compute.amazonaws.com
  Instance state: running
  IPv4 Public IP: XX.XXX.XXX.XXX
  Instance type: r4.xlarge
  IPv6 IPs: -
  Elastic IPs:
  Private DNS: ip-XXX-XX-XX-XX.us-east-2.compute.internal
  Availability zone: us-east-2b
  Private IPs: XXX.XX.XX.XX
  Security groups: default. view inbound rules. view outbound rules
  Secondary private IPs
  Scheduled events: No scheduled events
  VPC ID: vpc-ce0c17a6
  AMI ID: ubuntu/images/hvm-ssd/ubuntu-bionic-18.04-amd64-server-20191002 (ami-0d5d9d301c853a04a)
  Subnet ID: subnet-b3f881c9
  Platform: -
  Network interfaces: eth0
  IAM role: -
  Source/dest. Check: True
  Key pair name: mykeyb
  T2/T3 Unlimited: -
  Owner: XXXXXXXXXXXX
  EBS-optimized: False
  Launch time: November 26, 2019 at 5:43:37 PM UTC-5 (1 hour)
  Root device type: ebs
  Termination protection: False
  Root device: /dev/sda1
  Lifecycle: spot
  Block devices: /dev/sda1
  Monitoring: basic
  Elastic Graphics ID: -
  Alarm status: None
  Elastic Inference accelerator ID: -
  Kernel ID: -
  Capacity Reservation: -
  RAM disk ID: -
  Capacity Reservation Settings: Open
  Placement group: -
  Partition number: -
  Virtualization: hvm
  Reservation: r-XaecaXXbfXacXXXXX
  AMI launch index: 0
  Tenancy: default
  Host ID: -
  Affinity: -
  State transition reason: -
  State transition reason message: -
  Stop - Hibernation behavior: Disabled
  Number of vCPUs: 4
  </code></pre>
  
  <p>Here are the Description details for the Free Instance I can connect to with <code>PuTTY</code>:</p>
  
  <pre><code>Instance ID: i-ZZdZZZZZ41cZZZZZZ
  Public DNS (IPv4): ec2-X-XXX-XXX-XX.us-east-2.compute.amazonaws.com
  Instance state: running
  IPv4 Public IP: X.XXX.XXX.XX
  Instance type: t2.micro
  IPv6 IPs: -
  Elastic IPs:
  Private DNS: ip-XXX-XX-XX-XXX.us-east-2.compute.internal
  Availability zone: us-east-2b
  Private IPs: XXX.XX.XX.XXX
  Security groups: launch-wizard-5. view inbound rules. view outbound rules
  Secondary private IPs:
  Scheduled events: No scheduled events
  VPC ID: vpc-ce0c17a6
  AMI ID: ubuntu/images/hvm-ssd/ubuntu-bionic-18.04-amd64-server-20191002 (ami-0d5d9d301c853a04a)
  Subnet ID: subnet-b3f881c9
  Platform: -
  Network interfaces: eth0
  IAM role: -
  Source/dest. check: True
  Key pair name: mykeyb
  T2/T3 Unlimited: Disabled
  Owner: XXXXXXXXXXXX
  EBS-optimized: False
  Launch time: November 22, 2019 at 12:16:56 AM UTC-5 (less than one hour)
  Root device type: ebs
  Termination protection: False
  Root device: /dev/sda1
  Lifecycle: normal
  Block devices: /dev/sda1
  Monitoring: basic
  Elastic Graphics ID: -
  Alarm status: None
  Elastic Inference accelerator ID: -
  Kernel ID: -
  Capacity Reservation: -
  RAM disk ID: -
  Capacity Reservation Settings: Open
  Placement group: -
  Partition number: -
  Virtualization: hvm
  Reservation: r-XXaXXXdfXXXXfXXXX
  AMI launch index: 0
  Tenancy: default
  Host ID: -
  Affinity: -
  State transition reason: -
  State transition reason message: -
  Stop - Hibernation behavior: Disabled
  Number of vCPUs: 1
  </code></pre>