An RPC error was thrown by the RPC Runtime process. Error 1630 1630

My exchange was running before without problems untill users on one  DAG server started getting Outlook Disconnected errors. I moved the databases to another DAG and everyting is ok. We have 3 CAS and 3 MBX, I am experiencing this problem on one DAG. When I move the user database to another DAG and do the same test, no problems.This is Exchange 2013 on Windows 2012R2 (Vmware). Checked internet but talks of CAS servers. Where do I start to troubleshoot

I ran testexchange connectivity on a mailbox on the problem server and got the error message

Attempting to ping the MAPI Mail Store endpoint with identity: 67f551f8-05b5-45db-b2d9-39b537eefdbd@sisecam.com:6001.   The attempt to ping the endpoint failed.   Additional Details   An RPC error was thrown by the RPC Runtime process. Error 1630 1630   Elapsed Time: 5293 ms.