In the JAVA SDK it's possible to set the endpoint, see here.
But how to do this for .NET SDK ? And what are the names to use?
Because it seems that a default endpoint "US East (Northern Virginia) Region" is always used.
You can also use an endpoint definitions delivered with Amazon SDK:
var ec2Client = new AmazonEC2Client(RegionEndpoint.EUWest1);
Since I believe hard-coding such values as endpoint addresses is not a best practice I use more configurable version (i.e. endpoint configured from web.config/app.config):
var region = RegionEndpoint.GetBySystemName("eu-west-1");
var ec2Client = new AmazonEC2Client(region);