Roots Discourse could not be resolved

Just noticed in nginx error.log:

2020/07/25 21:47:56 [error] 865#865: could not be resolved (110: Operation timed out) while requesting certificate status, responder:, certificate:

However, I can resolve the host manually (dig) just fine on that system.

What can I do to solve this? Different DNS for the web (Trellis) server?