When use a virtual device, cannot find pending device in the server

when i first attempt to use the Docker-run virtual device following the tutorial,I cannot find the the pending device in the server.
Then i check the syslog,

It seems that there is something wrong with the network,But I don’t know how to solve this problem, because Docker can ping the Internet normally,such as ping
Some error messages also appear on the server,such as

So how to solve the problem

I solve the problem.I can ping ip,such as,but can not ping hostname,such as ping hosted.mender.io. The reason is that the DNS server is wrong,then i change the file:/etc/resolv.conf,change the nameserver,now the virtual device can be found!