Roughly 50% of all resolve requests fail, regardless the program/tool.
ping google.comwill say "Network is unreachable",
- loading a site in Firefox will say "Unable to connect",
- Evolution will give error messages (about being unable to: load IMAP folders, send emails, etc).
If you need any information, such as the contents of files, let me know and I'll provide it.
Based on what it says here and here, I've already tried uncommenting "DNSSEC=no" in /etc/systemd/resolved.conf and then rebooting, but this doesn't fix the problem.