I bulldozed all the existing houseboats, then their bases, per the instructions by @ciane for fixing the issues with IP. I did bulldoze some of the ports and replaced them with ciane's replacement lots, and yes, I did have to unlock them first. But I left the ones she didn't make replacements for, so I could use them. So I reset the port I wanted to use, to put another base on. Maybe I should have set the ports to no houseboat in the beginning, instead of bulldozing the bases. I'll try adding a houseboat without setting the base size for the port instead and see how that goes.