问题关键是官方连不上了。
解决办法就是使用国内加速站：比如https://docker.nju.edu.cn
可以把此站加入群晖的镜像站中并使用，不服错了。但还是搜不出来镜像
两个办法：
1 使用SSH连接到群晖用命令下载，然后到自带的管理页面的镜像页中就可以看到刚刚下载的镜像了
操作：
先搜索需要的镜像
aaaa@DS918PLUS:~$ sudo docker search ubuntu
Password:
NAME DESCRIPTION STARS OFFICIAL AUTOMATED
ubuntu Ubuntu is a Debian-based Linux operating sys… 17003 [OK]
websphere-liberty WebSphere Liberty multi-architecture images … 298 [OK]
ubuntu-upstart DEPRECATED, as is Upstart (find other proces… 115 [OK]
ubuntu/nginx Nginx, a high-performance reverse proxy & we… 112
neurodebian NeuroDebian provides neuroscience research s… 107 [OK]
ubuntu/squid Squid is a caching proxy for the Web. Long-t… 88
ubuntu/bind9 BIND 9 is a very flexible, full-featured DNS… 83
ubuntu/apache2 Apache, a secure & extensible open-source HT… 72
open-liberty Open Liberty multi-architecture images based… 64 [OK]
ubuntu/mysql MySQL open source fast, stable, multi-thread… 61
ubuntu/prometheus Prometheus is a systems and service monitori… 60
ubuntu-debootstrap DEPRECATED; use “ubuntu” instead 52 [OK]
ubuntu/kafka Apache Kafka, a distributed event streaming … 47
ubuntu/postgres PostgreSQL is an open source object-relation… 37
ubuntu/redis Redis, an open source key-value store. Long-… 22
ubuntu/dotnet-aspnet Chiselled Ubuntu runtime image for ASP.NET a… 18
ubuntu/dotnet-runtime Chiselled Ubuntu runtime image for .NET apps… 16
ubuntu/dotnet-deps Chiselled Ubuntu for self-contained .NET & A… 15
ubuntu/jre Distroless Java runtime based on Ubuntu. Lon… 13
ubuntu/zookeeper ZooKeeper maintains configuration informatio… 13
ubuntu/grafana Grafana, a feature rich metrics dashboard & … 9
ubuntu/prometheus-alertmanager Alertmanager handles client alerts from Prom… 9
ubuntu/memcached Memcached, in-memory keyvalue store for smal… 5
ubuntu/cortex Cortex provides storage for Prometheus. Long… 4
ubuntu/cassandra Cassandra, an open source NoSQL distributed … 2
然后拉取：关键是指定镜像站
aaaa@DS918PLUS:~$ sudo docker pull docker.nju.edu.cn/library/ubuntu:16.04
16.04: Pulling from library/ubuntu
58690f9b18fc: Pull complete
b51569e7c507: Pull complete
da8ef40b9eca: Pull complete
fb15d46c38dc: Pull complete
Digest: sha256:1f1a2d56de1d604801a9671f301190704c25d604a416f59e03c04f5c6ffee0d6
Status: Downloaded newer image for docker.nju.edu.cn/library/ubuntu:16.04
docker.nju.edu.cn/library/ubuntu:16.04
2 第二个办法就是安装Portainer
这个也是用方法1：安装docker镜像 汉化好的镜像名称为 6053537/portainer-ce
sudo docker pull docker.nju.edu.cn/6053537/portainer-ce
下载好后运行
sudo docker run -d –restart=always –name=”portainer” -p 9000:9000 -v /var/run/docker.sock:/var/run/docker.sock -v portainer_data:/data 6053537/portainer-ce
然后打开http://网盘IP:9000
第一次进入就设置一个12位的密码
然后配置好源，就可以web页直接下载镜像了