Internet connection dropped after docker start

Question

I have Ubuntu 16.04 and every time I start a docker container and my internet connection gets dropped.

I think, there is conflicts with ip addresses or ports docker containers and internet connection. But maybe I am wrong. How can I solve this issue?

Here is my settings:

/etc/NetworkManager/NetworkManager.conf

[main]
plugins=ifupdown,keyfile
dns=dnsmasq

[ifupdown]
managed=false

[keyfile]
unmanaged-devices=interface-name:docker0;interface-name:vmnet*;interface-name:vboxnet*;interface-name:br-2164968a2156;interface-name:veth*;

nmcli dev shows

DEVICE           TYPE      STATE         CONNECTION         
br-913cc3bb855c  bridge    connected     br-913cc3bb855c    
enp3s0           ethernet  connected     Wired connection 2 
wlp2s0           wifi      disconnected  --                 
docker0          bridge    unmanaged     --                 
lo               loopback  unmanaged     -- 

/etc/network/interfaces

auto lo
iface lo inet loopback

Answer 1

systemctl stop docker
iptables -t nat -F
ifconfig docker0 down
brctl delbr docker0
systemctl start docker