$ aws s3 ls
Could not connect to the endpoint URL: \"https://s3.us-east-1a.amazonaws.com/\"
What could be the problem?
Everyone has different defaults, and interestingly it will change after time. As an example, first I was on global, and then after 15 minutes it shows Ohio (which is us-east-2).
The best approach is to check it during your work -- in console of your AWS working area, just set it on the right above side near your name on top bar check your region name and click on the down arrow to see your region.
In AWS CLI type aws configure or aws2 configure, give your access and secret id, then during default region, write your region and press Enter.
You will definitely get access to specific region set and it will work.