Re: Windows Server
"Curious here: how will all of this work with captive portals?
i.e. when I connect to the 'free' wifi network on the subway, a captive portal opens which I have to click an 'I agree' button."
Perhaps some of them will break.
If the user is first redirected to a web page with only an IP address - the captive portal should work.
At least Firefox can be configured to use traditional DNS as a fallback if DoH queries fail. (network.trr.mode=2) So it still should work.