I did the fresh install ...three times since yesterday
do You mean this alternative installation? Does it make any difference compared to typical instalation which in my case is good, everything works fine. I can access, docker, portainer, add drives, shares, install and use duckdns, airsonic, syncthing, filebrowser. The only problem is wanishing GUI of OMV. Since installed everything i need, and still can install components via portainer or yacht that would be enough. But i forgot to set SAMBA shares and can't add external drive to nextcloud
It sounds like you're setting up something to take port 80... which OMV needs.
Log in via SSH or Console as root and run omv-firstaid One of the options is to 'Configure web control panel'.. choose that and when it asks for the port, change it from 80, to another port on your server that is not in use (say, 81).. Then save the changes.
Now to get to the OMV webui try going to yourserverip:port