Jgroups Stack Possible Unicast Issues in EC2

<config xmlns="urn:org:jgroups" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="urn:org:jgroups http://www.jgroups.org/schema/JGroups-3.1.xsd">
    <UDP
        ip_mcast="false"
        tos="8"
        ucast_recv_buf_size="128k" ucast_send_buf_size="128k"
        ip_ttl="${jgroups.udp.ip_ttl:128}"

        loopback="true"
        discard_incompatible_packets="true"

        max_bundle_size="64k"
        max_bundle_timeout="30"
        enable_bundling="true"

        enable_diagnostics="false"
        thread_naming_pattern="cl"

        timer_type="new"
        timer.min_threads="4" timer.max_threads="10"
        timer.keep_alive_time="3000"
        timer.queue_max_size="500"

        thread_pool.enabled="true"
        thread_pool.min_threads="2" thread_pool.max_threads="8"
        thread_pool.keep_alive_time="60000"
        thread_pool.queue_enabled="true"
        thread_pool.queue_max_size="100"
        thread_pool.rejection_policy="discard"

        oob_thread_pool.enabled="true"
        oob_thread_pool.min_threads="2" oob_thread_pool.max_threads="8"
        oob_thread_pool.keep_alive_time="60000"
        oob_thread_pool.queue_enabled="false"
        oob_thread_pool.queue_max_size="100"
        oob_thread_pool.rejection_policy="discard"
        />
        <!-- this is an internal protocol that uses AWS api calls to discover hosts -->
    <EC2_PING />
    <MERGE2 min_interval="10000" max_interval="30000" />
    <FD_SOCK start_port="8000" />
    <FD_ALL timeout="10000" />
    <VERIFY_SUSPECT timeout="10000" />
    <pbcast.NAKACK use_mcast_xmit="false"
               retransmit_timeout="100,300,600,1200,2400,4800" discard_delivered_msgs="false" />
    <UNICAST />
    <pbcast.STABLE stability_delay="500" desired_avg_gossip="5000" max_bytes="1m" />
    <pbcast.GMS print_local_addr="false" join_timeout="3000" view_bundling="true" />
    <UFC max_credits="200k" min_threshold="0.2" />
    <MFC max_credits="200k" min_threshold="0.2" />
        <!-- ultimately this was the problem moving this down to 16k fixed the issue (32k may be fine) -->
    <FRAG2 frag_size="60k" />
    <COUNTER />
    <PEER_LOCK />
</config>