There's a continuous archipelago from Indonesia to Easter Island. Polynesians were (are) fantastic at wayfinding. No one tried to spread Islam to some local natives and hear stories about people on another island and rinse repeat all the way down the island chain? Or just, go exploring? Wash adrift and try to find their way back home? If they did, why wasn't contact maintained?
I'm confused by this question. There are no Polynesians in Indonesia. There is hardly a "continuous" archipelago all the way to Easter Island. What's more is that there are literally over 1000 languages spoken in Oceania so it's not particularly easy to make sustained contact with a large group of people. Distances in the Pacific are long and difficult to traverse and Polynesia and Micronesia (where the societies with the best distance navigators are) are very isolated from the Old World. Of course, the Indonesian archipelago had lots of trade with the Old World (indeed, was part of the Old World as the label is normally applied).