Unidentified devices and Mullvad VPN

Hello, I just configured Mullvad's VPN app on both Android and iOS to use NextDNS. The problem is that all the devices' analytics are lumped together. I can't figure out how to isolate the analytics pertaining to the correct device. I'm reading that if I could use a secure protocol, the device name would be sent to NextDNS. Neither Mullvad nor Proton's VPN apps allow me to use secure protocols. I can only enter both IPv6 addresses into the app so that I can use their VPNs, but with NextDNS rather than the VPN's own DNS. 

If I can't get the device information sent to NextDNS' server, then how can I use Proton/Mullvaf and NextDNS and have my device information sent?