masOS DNS over HTTPS profile causing issues

One new feature in macOS 11 is the ability to encrypt your DNS without needing a VPN app. To do so, I’ve been using this system profile for ~7 months now.

All it does it set my system DNS to use DOH to 1.1.1.2 and 1.0.0.2, plus the IPv6 equivalents. This has been working perfectly… up until a few days ago.

Now what’s happening is that, in some non-browser applications, they seem to be having troubles resolving domain names. The app where I noticed it first was Slack. It got stuck loading new messages. Screenshot:

After emailing with Slack support, they said: " It seems your device is unable to resolve an IP address for app.slack.com and slack.com." They’re seeing this error in my logs:

t=60011 [st=30004]   -HOST_RESOLVER_IMPL_PROC_TASK
                      --> net_error = -105 (ERR_NAME_NOT_RESOLVED)
                      --> os_error = 8
                      --> os_error_string = "nodename nor servname provided, or not known"

Per them, this means that my OS is “unable to complete DNS resolution on behalf of the Slack desktop application.” As soon as I remove the profile though, Slack starts working again right away.

The odd thing is that the Slack web client works perfectly in Chrome, and Chrome is set to use secure DNS as well, “with your current service provider”, which I assume means it’s just using the system DNS the same as everything else?

What’s happening here? Something on Cloudflare’s side? Is my profile configured incorrectly? And if so, how has it been working this entire time?

Any help would be appreciated. :slight_smile: