You can clone with
Pull replication fails on an iOS device when WiFi is off and the device is using a cell network (3G).
When on WiFi push and pull work fine.
When on cell network push works fine but when pulling updates the operation times out.
This was previously posted on the CouchCocoa repo but as the issue involves replication it has been reposted here. Please see the following comment which may or may not help with this issue. couchbaselabs/CouchCocoa#22 (comment)