Docker became unresponsive after VPN connection

Expected behaviour

run docker command:
docker ps

Actual behavior

Error response from daemon: Bad response from Docker engine

Information

Output of diagnose:
[OK] Moby booted
[OK] driver.amd64-linux
[OK] vmnetd
[OK] osxfs
[OK] db
[OK] slirp
[OK] menubar
[OK] environment
[OK] Docker
[OK] VT-x

it actually stopped here, hangs I think.
so if there are more test to be run, i am not able to see them.

here are system logs too:

May 27 19:00:43 -MacBook Docker[13230] : Proxy settings have changed
May 27 19:07:45 -MacBook Docker[13228] : server loop caught Failure(“Caught EOF on underlying FLOW”): no further requests will be processed
May 27 19:07:45 -MacBook Docker[15549] : EOF reading packet from Unix domain socket: closing
May 27 19:07:45 -MacBook Docker[15549] : Failed to read hello from client

tested on a 2015 macbook, OS X 10.11.5

Steps to reproduce the behaviour

toggle VPN connection does not guarantee reproduce this err

after a while about 10 mins, docker engine is alive. however my containers are all stopped