Replication checklist. If replication does not work, please check following things,
1) Make sure that you are not replicating over NAT. Replication over NAT does not work because the IP is used as part of the server authentication.
2) Next, check to make sure that you are not sending or receiving the distribution table. On the primary server, the distribution table should not be checked in the send list, and on the secondary, the distribution table should not be checked for receive.
3) Then I would like you to check in the secondary server's partner list, to make sure that the primary is not listed. You should not enter the primary server into the partner list on the secondary server. However, the primary server should have all secondary servers listed in its partner list.
4) Ensure that the secondary server has it's replication scheduling set to "manual".
5) Please verify that your servers are all running exactly the same ACS version and build.
6) Also check if we have any firewall in between two acs servers. Most firewalls have skinny inspection enabled by default. Since ACS replication works on port 2000 which is also used by skinny, the firewall will drop the replication packets assuming it is a “malformed skinny packet”.