We have a client who is downsizing their infrastructure. Currently they have a Win2003 DC and a Win2012 DC on premise, and a Win2008R2 DC hosted in our datacenter. I'm trying to demote the DC in our datacenter, but I keep getting an "RPC Server Unavailable" error pointing to the FSMO server (Win2012) when I run dcpromo. DNS checks out, repadmin /showrepl shows no errors, and repadmin /syncall completes fine. DFS was working flawless till I disabled it prior to the demotion. There is a SonicWall TZ210 at both ends, and no changes have been made to them for well over a year.
I was able to successfully demote the on-premise Win2003 server with no errors.
A little confused as to where else to look to try and find the problem.