Aether not only correctly predicted that light would act as waves, but also incorrectly predicted that the Earth's motion with respect to aether should affect the perceived speed of light.

I don't know anything about old ideas about aether, but I've wondered why it was wrong, and whether the aether-idea is really conclusively wrong or whether someday science could return to that idea.

Does "aether" necessarily mean that the observed speed of light may vary? In particular, what is packed into the word "aether" that demands this?

...I'm wondering if a different "aether" that doesn't require observer-dependent light speeds may be no less weird than current assumptions we have about how light propagates?