[c0nsumer]

Client isolation is done at L2. You can't add exceptions for IP ranges / protocols / etc this way because that's up the stack. Even if devices can learn about each other in other ways, isolation gets in the way of direct communication between them.

[oasisbob]

The paper makes the point that you need to consider L3 in client isolation too - they call this the gateway bouncing attack. If you can hairpin traffic for clients at L3, it doesn't matter what preventions you have at L2