Sync gateway to sync gateway replication

Hi. I am trying to do something that is rather ‘out of the box,’ as they say. Here’s what I am trying to do:
I have one Couchbase Server instance living in a cloud service. This is the pretty server, that I have full control of all the time.
I have another Couchbase Server instance that I do not always have control of (read: the IP address can change).
I am trying to use the Sync Gateway to keep these two in sync. I have set up Sync Gateway on both servers, and set them up according to the documentation, including the replication in accordance with this. However, my replication isn’t working. We are using CB Server Community Edition 6.5.1.

Here’s a sample of my serviceconfig.json. I also attempted to just make a local-only replication via sync gateway, but that also didn’t work.
(I had to edit my databases because the forum wouldn’t let me post more than two links in this post…)
{
“log”: [""],
“databases”: {
“administration”: {
“server”: “localhost”,
“bucket”: “administration”,
“username”: “Administrator”,
“password”: “administrator”,
“enable_shared_bucket_access”: true,
“users”: {
“GUEST”: { “disabled”: false, “admin_channels”: ["
"] }
}
},
“administration_backup”:{
“server”: “localhost”,
“bucket”: “administration_backup”,
“username”: “Administrator”,
“password”: “administrator”,
“enable_shared_bucket_access”: true,
“users”: {
“GUEST”: { “disabled”: false, “admin_channels”: ["*"] }
}
}
},
“replications”:[
{
“source”:“administration”,
“target”:“http://remote_db:0000000@13.90.56.47:4985/administration”,
“continuous”:true
},
{
“source”:“administration”,
“target”:“administration_backup”,
“continuous”: true
}
]

}

Is there a need for Sync Gateway outside of your inter cluster sync ? Assuming its just 2 clusters (based upon your description) and if you are not using Sync Gateway , then why aren’t you considering XDCR?