I am struggle with the same issue. When manually mount my external drive, NCP can be installed within a folder on the drive but OMV cannot share folders with this drive. When I mount the drive through OMV I get the permission issue stated above.
do you mean the network within portainer/docker? I created a new network with macvlan driver and IPv4 gateway = IP of my router. I use this network for both containers, pihole and nextcloud.
But to be honestā¦I donāt think I will continue with this setupā¦every now and again we have the problem that the container just stopps or I need to reinstall it because it is not working anymore for whatever reason, etc. It is really frustrating, because it is not working reliably for one week. I want a system which is reliable without needing to reconfigure it nearly every week or so. So I think I will switch from OMV + docker to ājust nextcloudpiā appliance and will test this.
I hope that you have more luck with this combination than I have