Hello @Odonabit 

Do you want to set up Access Control -White list on router and only permit certain devices to get internet from router? 

It is not very recommended doing whitelisting when routers work with a wifi extender.  Range extender ,working as a proxy,  it will replace each of its clients’ MAC address with a virtual MAC address generated automatically by Range Extender. Thus the router will take the virtual MAC address of the clients as their real MAC address, this will cause trouble when you set up Whitelist or Parental Control settings, check here for more details:  How to set up Mac Filtering on router (blue UI) to control the devices connected to the Range Extender?

If you still prefer a try, you could try to set rules as below and see if this works: 

For clients connected to  router : 
- Add real Mac address of Camera in  Router Whitelist

- Add real Mac address of Range extender (add both 2.4Ghz& 5Ghz Mac of RE if its a dual-band extender)

- Add virtual Mac address of Camera (could be found on extender web page) in Router Whitelist 

For clients connected to Range extender 
- Add Mac address of Cameras in Range Extender Whitelist

How to set access control on my range extender (new logo)?