主要问题是：
# systemctl status systemd-resolved.service
systemd-resolved.service -
Network Name Resolution Loaded: loaded (/lib/systemd/system/systemd-resolved.service; enabled; vendor preset: enabled)
Active: failed (Result: resources) since Wed 2021-05-19 11:15:15 UTC; 23s ago
Docs: man:systemd-resolved.service(8)
https://www.freedesktop.org/wiki/Software/systemd/resolved
https://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers
https://www.freedesktop.org/wiki/Software/systemd/writing-resolver-clients
May 19 11:15:15 kv-server systemd[1]: systemd-resolved.service: Service has no hold-off time, scheduling restart.
May 19 11:15:15 kv-server systemd[1]: systemd-resolved.service: Scheduled restart job, restart counter is at 5.
May 19 11:15:15 kv-server systemd[1]: Stopped Network Name Resolution.
May 19 11:15:15 kv-server systemd[1]: systemd-resolved.service: Start request repeated too quickly. …