Connection Priority in domino

I found a document in the forum about connection Priorities for servers:- Local Area Network

  • Network Dialup

  • Notes Direct Dialup

  • Passthru server

  • Hunt group of passthru servers

I have three servers

ServA → Domino directory server

ServB → Used for Clients and servers to passthru to the directory server for security purposes

ServC → In a branch with a phone line and a DSL connection

I would like my connection priority to have the passthru server above the notes Direct Dialup does anyone know how to do that?

I tried changing the routing cost to 1 for the passthru connection and the com ports to 7. I thought 7 would be a lucky number. I am not convinced this is working. Any ideas? It seems all my mail is going through the phone line. The Server I am replicating with (servA)has a LAN connection to my server so mail is transferring over the Internet but it is coming back over the phone line (from ServC).