I was on the quest to beat Guzma, trying to get Lillie and Cosmog back from Team skull on Aether Island, Guzma beat me, and I went to the nearest poké-center (Ula Ula Island Tapu Village), and I can't seem to find a way back. The boats from island to island are undergoing "fixing", and I can't use them.
11 Answer
If you go to the Malie City marina, which is on the far eastern end of the Ula Ula island, Gladion should be waiting with a boat to take you back to Aether Paradise.
