Couchbase Server is constructed using a series of components, each requiring access to a different port. It's common to encounter errors when trying to use Couchbase for the first time, due to blocked ports. You're more likely to have fewer port restrictions on your development machine than on your production servers, but it's still important to make sure you have at least ports 8091, 8092, 11210, and 11211 open. Running a cluster requires more port access, but for development, you'll need to have the web admin accessible (8091) and the API and client endpoint ports open (8092, 11210, and 11211).