Thanks for clarifying. Will keep that in mind if I decide to run multiple masternodes.

Unsure why it didn't work without specifying the port though since reading the thread very few people have encountered the issue and would have expected the OP to have been updated if it were wrong. Found the answers through some example DASH masternode configs and they all showed : in a single masternode setup and since then it has worked - so not going to touch the config now .