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Host-OS restart and busy ports

I started learning docker (Docker version 18.06.1-ce, build e68fc7a) and I use it on Linux ubuntuserver 4.15.0-34-generic. I created container by this command:

sudo docker run -d --privileged --name FBSServer --hostname BACKUPSERVER --restart=always -p 4530:4530 -p 4531:4531 -v /home/adminek/synology:/fbs ferro/backupsystem FBS_Server

As you see container is listening on ports 4530 and 4531. When I ran this command for the first time, everything was OK. The container is running and I can communicate with an app using ports 4530/4531.

But after rebooting the host system the container is in Exited state

root@ubuntuserver:~# docker ps -a
CONTAINER ID        IMAGE                COMMAND                  CREATED             STATUS                            PORTS               NAMES
6e77a4729847        ferro/backupsystem   "/ FBS_Server"   7 hours ago         Exited (128) About a minute ago                       FBSServer

and I can not start the container. I see this:

root@ubuntuserver:~# docker container start FBSServer
Error response from daemon: driver failed programming external connectivity on endpoint FBSServer (c2afb35a61a18c65e8c306bbf36d4e2c9cdf428aafa386e12281d2d9e714b238): Error starting userland proxy: listen tcp bind: address already in use
Error: failed to start containers: FBSServer

In order to start I have to type these commands:

root@ubuntuserver:~# lsof -i :4530 | grep LISTEN
docker-pr 1328 root    4u  IPv6  35086      0t0  TCP *:4530 (LISTEN)
root@ubuntuserver:~# lsof -i :4531 | grep LISTEN
docker-pr 1316 root    4u  IPv6  35059      0t0  TCP *:4531 (LISTEN)

Then I kill the processes (in this example 1328 and 1316) and then I can start container by typing:

docker container start FBSServer

So the question number 1:
Why after rebooting host system ports are “busy”?

and number 2:
Why sometimes after rebooting host system I see that the changes in container were not saved? In other words - after reboot and made commands from above container is up, but it is in state without last changes I made a while before reboot the host.

I noticed that problem is connected with Ubuntu Server. On Ubuntu Desktop or LInux Mint (17, 18 and 19) everything works correctly. On desktop versions docker runs container and ports are not busy so you don’t have to do anything in order to start container. It starts automatically with OS. Problem is present only in server edition of linux. What exactly? I don’t know…