OK, what did I do wrong?

I had our network guru in today to segment our flat network and I had to change both the subnet mask and Router/gateway address that the servers are on. I did both of these in System Preferences. So I changed the subnet and gateway settings on my replica too, but my O.D. Master says it can't find the password service under OpenDirectory. What did I do wrong, and what's the best method to fix it?