有关 unbound 的 ssl-upstream 功能，高手求解

我设置了 OARC 的 DNS-over-TLS 的服务器，见： https://www.dns-oarc.net/oarc/services/dnsprivacy

我的配置文件：

# Unbound configuration file on windows.
# See example.conf for more settings and syntax
server:
# verbosity level 0-4 of logging
verbosity: 0

# if you want to log to a file use
logfile: "D:\unbound.log"

# on Windows, this setting makes reports go into the Application log
# found in ControlPanels - System tasks - Logs
use-syslog: no

# ip address to bind
interface: 127.0.0.1

# port to operate
port: 53

# if yes, perform prefetching of almost expired message cache entries.
prefetch: yes

# use dns-over-tls
ssl-upstream: yes

forward-zone:
name: "."
forward-addr: 184.105.193.78@853

但是 DNS 查询就是不断地超时：

nslookup zh.wikipedia.org 127.0.0.1
服务器: localhost
Address: 127.0.0.1

DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
*** 请求 localhost 超时

高手求解？