There are "stats" - numerical and visual - not as clear as I'd like but you can get an idea of who's doing what and how much.
BUT NOT WITH ZF7363, they do not support this level of reporting even if your ZD is on 9.8 or later.
Two screenshots from ZD1125 on 9.10 b218
Kings group (all on 7363) shows no useful traffic data...as in none.
Oak group (all on R500) shows usage per client...for instance the big blue wedge is on IP 172.16.19.70 and you can see that IP belongs to an ipad called Nursery12. Not brilliant but good enough if I needed to chase down a hog (not a worry in my scenario).
Pics are 1280px so you can see the detail.
KINGS site (7363)
![Image_ images_messages_5f91c422135b77e24797d3e0_d57fe7f81b3a4e897b3c83dee1c7114f_RackMultipart2015042914423xlxc-db5ba83b-b730-4cbb-aea4-a3bd9dbb02bf-1716679279.jpg1430311354 Image_ images_messages_5f91c422135b77e24797d3e0_d57fe7f81b3a4e897b3c83dee1c7114f_RackMultipart2015042914423xlxc-db5ba83b-b730-4cbb-aea4-a3bd9dbb02bf-1716679279.jpg1430311354](/t5/image/serverpage/image-id/184iBFE93E76CC6A4D94/image-size/large?v=v2&px=999)
OAK site (R500)