How do you connect resources to your empire's trade network?

I'm playing on an archipelago map for the first time and I can't figure out how to move resources around my empire.

I have Fishing Quays in each settlement, but all of my resources outside my capital say "Settlement is not connected to your Empire's Trade Network."

What do I need to do?

EDIT--I was able to confirm I was running into a bug. I reported it.