A picture would help. I’ve had the best luck growing Vandas bare root: not potted. You’d probably have the best luck setting it up so the roots can hang free.
Check out this "sticky" on the Vanda forum Vandas in Glass Vases for some good ideas about growing these bare-root in vases. If you do pot, use large bark, just to cover the roots. But mostly, Vandas really do not take well to potting - they like their roots exposed to the breezes. Lots of humidity, lots of air.