When docker suddenly stops working via tcp...

gistfile1.txt

#Enable the Remote API on a New Socket

# create file to make Docker available on a TCP socket on port 2375.

touch /etc/systemd/system/docker-tcp.socket 

cat > /etc/systemd/system/docker-tcp.socket <<EOF
[Unit]
Description=Docker Socket for the API

[Socket]
ListenStream=2375
BindIPv6Only=both
Service=docker.service

[Install]
WantedBy=sockets.target
EOF

# Then enable this new socket:

systemctl enable docker-tcp.socket
systemctl stop docker
systemctl start docker-tcp.socket
systemctl start docker

# Test that it’s working:

docker -H tcp://127.0.0.1:2375 ps