We’re seeing something that feels similar using the latest Ruby SDK: Ruby SDK Times Out with Back-to-Back Queries
In our case, this is two Ubuntu instances in the same region and same security group, but two different availability zones (us-west-2a test instance hitting us-west-2c database box). We’re using single server 4.1.1-5914-enterprise with no other client connections but the test code, and we’re using the 1.3.14 ruby gem with libcouchbase 2.6.2.
I know the cross post is annoying, but hopefully not too confusing and potentially helpful if this could be libcouchbase related instead of an issue with couchbase itself.