Some server has specified settings wrote by command “route -p” to deal with multiple internet or intranet connections. To make it work with RRAS, the option “if <number>” must be provided with each route command.
If you’re planning to upgrade such a server to Windows Server 2012 R2, be careful, you may have to get a console connection. Through upgrading process will not failed or at least give you any warning about route settings, after it done, the interface number of NIC (network interface card) will be changed. It means you have to remove and add the related persistent routes to resume the remote connection before you can use this server again.
If you cannot get a console, you may want to disable RRAS, remove the “if <number>” parameter from the route command before upgrading.