Common Mistakes I See Students Make

By Ravindra Bagale Last updated: 25 September 2026

Selecting the wrong region (e.g. N. Virginia) and then "losing" the instance. The console shows resources only for the selected region.
SSH source set to My IP, then changing Wi-Fi/mobile hotspot. Your public IP changes and SSH times out — update the rule.
Wrong username: ubuntu@ for Amazon Linux, or ec2-user@ for Ubuntu → Permission denied (publickey).
Forgetting chmod 400 on the .pem file.
Typing https:// for a server that only has HTTP and thinking the server is down.
Terminating when they meant to stop, and losing the root volume.
Leaving instances, Elastic IPs and volumes running after the lab and getting a bill.