The remote host closed the connection

I have a Couchbase server (v5.1.1) on a remote server. I want my nodejs application to open a bucket from that Couchbase instance but it failed with this error:

code:45
message:"The remote host closed the connection"
stack:"CouchbaseError: The remote host closed the connection"

I use SSH to open a tunnel to the 8091 port. Here is my PuTTY configuration

image

And here my code to open the bucket:

const cluster = new couchbase.Cluster(`couchbase://localhost:9201?detailed_errcodes=1`);
cluster.authenticate(`${process.env.COUCHBASE_ADMIN_USER}`, `${process.env.COUCHBASE_ADMIN_PASSWORD}`);

const usersBucket = cluster.openBucket(`${process.env.USERS_BUCKET}`, function(err) {
  if (err) {
    console.error('Got error: %j', err);
  }
});

Any idea how to solve this? Thanks.