The documentation for Atlas to Atlas migration via mongosync has confusing examples (generic for on-prem servers) and a wrong example for SRV connection.

Documentation

• First example:

  cluster0:
  mongodb://clusterAdmin:superSecret@clusterOne01.fancyCorp.com:20020,clusterOne02.fancyCorp.com:20020,clusterOne03.fancyCorp.com:20020
  cluster1:
  mongodb://clusterAdmin:superSecret@clusterTwo01.fancyCorp.com:20020,clusterTwo02.fancyCorp.com:20020,clusterTwo03.fancyCorp.com:20020 

  Correction proposal:

We should use `cluster1Name.ab123.mongodb.net:27017` and `cluster2Name.ab123.mongodb.net:27017` as generic name for an Atlas server name for each case and ensure we replace 27017 as default port instead of 20020 for all the examples on the linked documentation.

Using a generic server and a port different from the Atlas default connection port may cause confusion at the time to connect.

• SRV final example:

   mongosync \
     --cluster0 'mongodb+srv://clusterAdmin:superSecret@clusterOne01.fancyCorp.com:20020/' \
     --cluster1 'mongodb+srv://clusterAdmin:superSecret@clusterTwo01.fancyCorp.com:20020/'

   

Correction proposal:

This command is incorrect, the SRV connection string doesn't includes the port in Atlas. The correct command should be:

mongosync \    
--cluster0 'mongodb+srv://clusterAdmin:superSecret@cluster1name.ab123.mongodb.net/'\   
--cluster1 'mongodb+srv://clusterAdmin:superSecret@cluster2Name.ab123.mongodb.net/' 

Let me know if you need any further clarifications on this.