I have set Quad9 as DNS resolver on my router and wanted to check via dnslesktest and Mullvad Connection Check using the Brave browser on an iOS device whether everything works. Anyway, only Cloudflare came up as ISP. When I turned off iCloud Private Relay, Quad9 was displayed again.
I have tried it several times always with the same result.
I thought iCloud Private Relay only works within the Safari browser, or did I miss something?
Every browser on iOS is basically Safari under the hood, so it makes sense that Private Relay would work on other browsers. Wasn’t aware of that though, that’s pretty cool.
It does not work properly. My IP is still the same. Only the DNS resolver seems to be changed somehow by Private Relay instead of using the one I set on the router.
Hmmm that’s weird. Did you report it to Apple?
No 
But I probably should.
Yeah Private Relay is technically still in beta so probably just a bug they missed.
So, according to Apple Support, Private Relay is not only related to Safari, but to the entire iOS system, in connection to the WLAN network.
And they also pointed out the standard Private Relay article: About iCloud Private Relay - Apple Support
Well ok. Not so useful when my IP stays the same.
It’s not the whole system that goes through Private Relay, only Safari and other unencrypted traffic.
When I did the same test in the past, with Private Relay enabled, I was shown the DNS resolver I had set on my router.
Maybe they changed something. The DNS resolver is independent from the routing that your data takes over the web, though.
Be aware we don’t recommend to use Brave on iOS.
I use it mainly for bookmark synchronization.