Proxy 更改默认服务器后dnscrypt代理不工作

我已经在Ubuntu 16.10上安装了dnscrypt proxy form repos，然后根据以下命令对其进行了测试：

dig txt debug.opendns.com

得到了我所需要的：

dig txt debug.opendns.com

; <<>> DiG 9.10.3-P4-Ubuntu <<>> txt debug.opendns.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 48435
;; flags: qr rd ra; QUERY: 1, ANSWER: 6, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;debug.opendns.com.     IN  TXT

;; ANSWER SECTION:
debug.opendns.com.  0   IN  TXT "server m1.hkg"
debug.opendns.com.  0   IN  TXT "flags 20 0 70 7950800000000000000"
debug.opendns.com.  0   IN  TXT "originid 0"
debug.opendns.com.  0   IN  TXT "actype 0"
debug.opendns.com.  0   IN  TXT "source 31.192.111.175:43228"
debug.opendns.com.  0   IN  TXT "**dnscrypt enabled** (717473654A614970)"

;; Query time: 279 msec
;; SERVER: 127.0.2.1#53(127.0.2.1)
;; WHEN: Mon Feb 20 18:18:24 CET 2017
;; MSG SIZE  rcvd: 250

现在我没有看到“dnscrypt已启用”：

dig txt debug.opendns.com
;; 已截断，正在TCP模式下重试。
;  DiG 9.10.3-P4-Ubuntu txt debug.opendns.com
;; 全局选项：+cmd
;; 得到答案：
;; ->>HEADER看起来像是正常工作，这是正常的行为。安德鲁给了我一个答案：


DNSCRYPT_PROXY_RESOLVER_NAME=ns0.dnscrypt.is

dig txt debug.opendns.com
;; Truncated, retrying in TCP mode.

; <<>> DiG 9.10.3-P4-Ubuntu <<>> txt debug.opendns.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 44963
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;debug.opendns.com.     IN  TXT

;; AUTHORITY SECTION:
opendns.com.        2077    IN  SOA auth1.opendns.com. noc.opendns.com. 1487092083 16384 2048 1048576 2560

;; Query time: 442 msec
;; SERVER: 127.0.2.1#53(127.0.2.1)
;; WHEN: Mon Feb 20 18:23:51 CET 2017
;; MSG SIZE  rcvd: 92