It looks like when a server is rebooted, the pre-existing pipes that were attached to two blocks, now only attach to one and I can't configure it to reattach to the other. It feels like the world knows there's already a block there and refuses to redo the connection. We tried a different color pipe and it worked before, but now even that's not a solution. We can work around it by moving the tanks, chests, whatever else around.

Using version: Modern Industrialization 1.2.2
On Modpack: All of Fabric 5, 1.5.1

I even tried using world edit to replace the pre-existing pipes to air but nope. If I build in a different location the pipes connect as expected.

This generally happens whenever the game crashes unexpectedly, and the world data (including where pipes are) gets desynced from the actual blocks. You can enable debug commands and use /mi pipes clear x y z to remove any leftover pipe data.