How do I determine why my ehcache replication is not working?

I’m using Hibernate 5.1.0.Final with the accompanying ehcache module. I have two independent app servers (JBoss 7.1.3.AS.Final) — they are not clustered. I wanted to set up cache replication between the servers. I have the following ehcache.xml configuration …

<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../config/ehcache.xsd" updateCheck="false">

    <!-- This is a default configuration for 256Mb of cached data using the JVM's heap, but it must be adjusted
         according to specific requirement and heap sizes -->
    <defaultCache maxElementsInMemory="10000"
         eternal="false"
         timeToIdleSeconds="86400"
         timeToLiveSeconds="86400"
         overflowToDisk="false"
         memoryStoreEvictionPolicy="LRU">
    </defaultCache> 
    <cache name="main" maxElementsInMemory="10000" />

     <cacheManagerPeerProviderFactory
         class="net.sf.ehcache.distribution.RMICacheManagerPeerProviderFactory"
         properties="peerDiscovery=automatic, multicastGroupAddress=230.0.0.1,
         multicastGroupPort=4446, timeToLive=32"/>

    <cacheManagerPeerListenerFactory
        class="net.sf.ehcache.distribution.RMICacheManagerPeerListenerFactory"
        properties="port=40001,
        socketTimeoutMillis=2000"/>    

</ehcache>

I noticed when I restarted one of the servers, 15 minutes later, it had a dramatically smaller cache size than the first app server, indicating to me my replication was not working, despite the fact I don’t see any errors in the logs.

What’s wrong with my configuration above, or barring that, how do I determine if there is a network issue? I want to have the same ehcache.xml configuration file for each server if that’s possible (allows us to deploy the same WAR to every machine in the environment).