The socket connection was aborted - CommunicationException

This error can be caused by a number of things. While it was a timing issue in this case, it usually has nothing to do with timings, especially if the error is received immediately. Possible reasons are:

• The objects used as parameters or return types in your contract don't have parameterless constructors and are not decorated with the DataContract attribute. Check the classes used as parameters or return types, but also all the types used by the public properties of those classes. If you implement a constructor with parameters for one of those classes, the compiler will not add the default parameterless constructor for you anymore, so you will need to add that yourself.
• The default limits defined in service configuration are too low (MaxItemsInObjectGraph, MaxReceivedMessageSize, MaxBufferPoolSize, MaxBufferSize, MaxArrayLength).
• Some public properties of your DataContract objects are read-only. Make sure all public properties have both getters and setters.

that exception is not related to Circular Reference, it's just purely timing out as you try to pump tons of data over the wire.

The default values that comes with WCF are very very low (these have been changed in WCF 4 I believe). Have a read on these two blog posts, they should give you an idea on how to dethrottle your service:

Creating high performance WCF services

How to throttle a Wcf service, help prevent DoS attacks, and maintain Wcf scalability

Update: also, there are a number of different timeouts in the WCF configuration and depending whether it's the client or server you're talking about you need to update a different timeout clause... have a read of this thread on what each one means and you should be able to figure out which one you need to bump up. Or, you could just set every timeout to int.max if you don't really care if a call can take a loong time to complete.