Replication

Simple AD setup
2008r2

Dc LDN1
DC LDN2
domain : ldngtc.com

here is the following from repadmin /showrepl
Demoted LDN2 force removal then scrubbed DNS and metadata cleanup on LDN1 for all traces of LDN2 then DCPROMO LDN2 back to a DC and same thing ..  1722 RPC error , I've checked firewall don't see any issues. I'm starting to pull my hair out over this and I know it's going to end up being something simple . Please help

DC LDN1
Repadmin: running command /showrepl against full DC localhost
Default-First-Site-Name\LDN1
DSA Options: IS_GC
Site Options: (none)
DSA object GUID: 75ca430e-b9c9-418e-9cf4-f371b759fc4f
DSA invocationID: 7fd03eb2-1297-439f-bea9-3781077bf48c
==== INBOUND NEIGHBORS ======================================
DC=ldngtc,DC=com
    Default-First-Site-Name\LDN2 via RPC
        DSA object GUID: 114aed40-b5d5-4b7d-94c1-14fcb0c95663
        Last attempt @ 2014-03-14 09:15:51 was successful.
CN=Configuration,DC=ldngtc,DC=com
    Default-First-Site-Name\LDN2 via RPC
        DSA object GUID: 114aed40-b5d5-4b7d-94c1-14fcb0c95663
        Last attempt @ 2014-03-14 09:15:51 was successful.
CN=Schema,CN=Configuration,DC=ldngtc,DC=com
    Default-First-Site-Name\LDN2 via RPC
        DSA object GUID: 114aed40-b5d5-4b7d-94c1-14fcb0c95663
        Last attempt @ 2014-03-14 09:15:51 was successful.
DC=DomainDnsZones,DC=ldngtc,DC=com
    Default-First-Site-Name\LDN2 via RPC
        DSA object GUID: 114aed40-b5d5-4b7d-94c1-14fcb0c95663
        Last attempt @ 2014-03-14 09:15:51 was successful.
DC=ForestDnsZones,DC=ldngtc,DC=com
    Default-First-Site-Name\LDN2 via RPC
        DSA object GUID: 114aed40-b5d5-4b7d-94c1-14fcb0c95663
        Last attempt @ 2014-03-14 09:15:51 was successful.

DC LDN2
Repadmin: running command /showrepl against full DC localhost
Default-First-Site-Name\LDN2
DSA Options: IS_GC
Site Options: (none)
DSA object GUID: 114aed40-b5d5-4b7d-94c1-14fcb0c95663
DSA invocationID: 056a4e41-4680-4c47-87dd-5a77ca543ffa
Source: Default-First-Site-Name\LDN1
******* 61 CONSECUTIVE FAILURES since 2014-03-13 18:25:46
Last error: 1722 (0x6ba):
            The RPC server is unavailable.
Naming Context: CN=Configuration,DC=ldngtc,DC=com
Source: Default-First-Site-Name\LDN1
******* WARNING: KCC could not add this REPLICA LINK due to error.
Naming Context: CN=Schema,CN=Configuration,DC=ldngtc,DC=com
Source: Default-First-Site-Name\LDN1
******* WARNING: KCC could not add this REPLICA LINK due to error.
Naming Context: DC=ldngtc,DC=com
Source: Default-First-Site-Name\LDN1
******* WARNING: KCC could not add this REPLICA LINK due to error.