dhcp servre and lease help

hello,
i am bit confused
i have setup a dhcp server and everything work great.
But when i want to give a ip address to each client mac i have a problem
some client have a wireless router in their home but when i want to make a static ip i can’t find the wireless router mac i find the computers behind this router
so my question is: there is way to view the wireless router mac address and assign it a ip address and not for the computers behind this router.

Thanks For helping

Some Airport devices can be routers or bridges. I run into this.

There is a setting for this, but the Airport router complains about double nat and will sometimes revert back to bridging despite being set for router. If you have multiple publics you can 1:1 nat public:private.

There’s not much you can do unless you force the issue by only using static dhcp entries.