Talking about cellular/mobile connection here.

I am showing fd00:976a::9 and fd00:976a::10 for my cell DNS servers. A quick search says these are my cell provider's DNS servers.

Maybe both my cell and my home ISP use google dns then... I tend to use a VPN (wireguard) to use my own DNS (without my server having to be public)

Heh, interesting. Out of curiosity, where did you get the ROM you are using? I just bought a Sony phone and I compiled the AOSP image myself. Maybe the difference is based on where you got it.

I use lineageos, unmodified (on an oneplus 3T)

Heh, weird. I think lineage is fixed for my device now, so I'm going to try and install it. I'll see if it changes when it i s installed.

Thanks, I'm quite curious if it would be the same for you. Since it didn't use the server DNS I had set on my router, I assumed it was always using google DNS, I didn't look further.

I have a tablet that has vanilla LineageOS, and it is also using the DNS server that my router provided.

Out of curiosity, are you using DHCP? If you are then maybe the router you have is just forwarding the DNS setting it was given, and that is Google's DNS server.

Yes indeed, I'll double check. I have one router (my ISP one) that is definitely using google DNS. My other router is supposed to provide DNS and forward it to my own sever, but I'll have to double check my setup then...

I just installed vanilla lineageOS and I still have the same DNS servers I outlined earlier.

I am now wondering why yours are different.