It's not a bad idea to check out the clients page on that particular network. Possible causes include: Open SSID that allows alot of guest users Lot's of MAC randomization going on Connection to other network for example your WAN of your firewall is connected to a switch in your dashboard network and your ISP has traffic between customer that bleeds over to the WAN. Double counted traffic due to tracking via MAC address with L3 switch between them. ... View more