"Inaccessible host" deploying in non-default region

I have been using Serverless for about 4 weeks. Only since 2 weeks ago approximately, due to an update or the like, I started getting the following error on deployment (I redacted the bucket ID from the error):

 Serverless: Packaging service...
 Serverless: Excluding development dependencies...
 Serverless: Invoke aws:package:finalize
 Serverless: Invoke aws:common:moveArtifactsToPackage
 Serverless: Invoke aws:common:validate
 Serverless: Invoke aws:deploy:deploy

 Serverless Error ---------------------------------------

 Inaccessible host: `<redacted bucket id>.s3.eu-central-1.amazonaws.com'. This service may not be available in the `eu-central-1' region.

Is the S3 URL wrong?

My system:

OS:                     linux
Node Version:           6.11.2
Serverless Version:     1.23.0

I could reproduce it with win32 as well and I’m having the problem whether I supply the region in the command line or in serverless.yml. I also tried to remove the S3 buckets created by Serverless and removing the Cloudformation stacks, and starting over from scratch. If I don’t provide a region so that the default one is used, it works.

Given the few occurrences I found of this problem in internet, I imagine it might be a problem in my system. Whatever it is, any hint or idea is welcome.