  We discuss entanglement entropies in 4d interface CFTs based on 4d $\mathcal
N=4$ SYM coupled to 3d $\mathcal N=4$ degrees of freedom localized on an
interface. Focusing on the entanglement between the two half spaces to either
side of the interface, we show that applying the Ryu-Takayanagi prescription in
general leads to multiple natural entanglement entropies. We interpret the
different entropies as corresponding to different ways of assigning the 3d
degrees of freedom localized on the interface to the two half spaces. We
contrast these findings with recent discussions of universal relations for
entanglement entropies in 2d interface CFTs and formulate generalized relations
for 4d interface CFTs which incorporate our results.
