Great mod!

Ran into an error today. I had vanilla offshore pumps going into the input box, through a one-way valve then long underground pipe. This terminated at an output box and then directly into storage tanks.

When troubleshooting a flow issue, I disconnected and then attempted to reconnect underground ducts to the input box. I got a "cannot connect different fluid systems" error. I tried the other end, same error. I dumped the system, then tried again, no joy. I had to completely nuke that entire flow and re-create it to get it to start up again. I confirmed that it was all the same, water to water to water. Nothing else.

Any advice here or is this a bug?

Nothing that concern the mod, ask to game developers, all mod segments have one fluidbox per segment, so is impossible mix two fluids in a row...

What I suppose u have do but I'm not sure, is that somewhere in ur duct network, will be a path of another underground pipe, a vanilla one, and u ignore his existence when u try to connect all. In a moment something mix, or u don't look better the map.