Is that a mapping issue maybe? The skylight portal will take whatever section of the sky is behind it (colour tone etc) where as putting the vraysky on the texture slot will map the entire sky to the area of the plane light??
If you just want a little more light in your interior i’d suggest just using the colour temperature option on the plane light and setting it to 6500-8000 or something depending on lighting conditions…or stick with skylight if that#s working for you.