Build couchbase-server-6.6.0-7653 contains cbas-core commit 2ac11e4 with commit message:
MB-39278: handle external addresess for remote clusters

Build couchbase-server-7.0.0-2193 contains cbas-core commit 2ac11e4 with commit message:
MB-39278: handle external addresess for remote clusters

Verified in 6.6.0-7861:

Setup an EC2 instance and installed couchbase in it
Enabled Alternate address on it:

[root@ip-172-31-80-205 ~]# curl -v -X PUT -u Administrator:password http://localhost:8091/node/controller/setupAlternateAddresses/external -d hostname=ec2-3-237-24-39.compute-1.amazonaws.com

Installed travel-sample in this instance
Installed couchbase in a vagrant box
Set up remote link using alternate address of ec2 instance:

[root@node2-mad-hatter-testing-centos7 bin]# ./couchbase-cli analytics-link-setup -c localhost:8091 -u Administrator -p password --create --name testAltLink --dataverse Default --type couchbase --hostname ec2-3-237-24-39.compute-1.amazonaws.com --link-username Administrator --link-password password --encryption none
SUCCESS: Link created
[root@node2-mad-hatter-testing-centos7 bin]#

Created dataset on travel-sample using this link
Connected the link
Executed queries to make sure link works

Attaching screenshots of ec2 instance showing altaddr and query results on vagrant box instance

Build couchbase-server-6.6.2-9599 contains cbas-core commit 2ac11e4 with commit message:
MB-39278: handle external addresess for remote clusters