Hi Bob,
There are multiple ways to do it.
- Use a dedicated SSID for these devices and set the rate limit under WLAN advanced settings for entire WLAN.

- Enable application visibility and client fingerprinting and then OS policy under WLAN's advanced options.

Regards,
Syamantak Omer
Syamantak Omer | Community moderator | Staff TSE | CWNA | CCNA | RASZA | RICXI | Follow me at https://linkedin.com/in/syamantak-omer-5949b6124