Help with nfs4

[King_DuckZ]

Hello, I've set up a raspberry pi with archlinux to act as a nfs4 file server. It is working ok but I'm a bit confused about permissions: on the server, I've set acl permissions to the exported directory, because I want anything created in there to have 660 permissions and to belong to the nfsnobody group. It works from the server itself, but as I mount it on my sabayon machine, new files I create have the more usual rw-r----- permissions.
My exportfs specifies the acl option, and my mount command specifies it as well. Anyone can help with that? I want all files and directories created to have rw group permissions.