The last hour I did a brand new installation of OMV v5 (over Debian 10). With latest OMV5-extras I’ve installed docker and tried to install Portainer, but I didn’t have access to the web interface. Even OMV showed me that Portainer was successful installed.
Than I’ve tried cockpit and this worked perfect. I could open the Webinterface of cockpit.
So the best way right now to use Portainer is to install it by hand (via command line)
Edit: sorry, but even installing Portainer by hand didn’t work. I don’t know what’s going on here
OMV-Server-HW: MoBo Fujitsu D3417-B2 (Intel-LAN), Intel Xeon E3-1245 v6 Kaby Lake (4x3.70GHz), 16GB-Ram ECC UDIMM, 1x512GB SSD Samsung 850 Pro (sda2 - 30GB system, 4GB swap, sda5/rest - for work), 1x 10TB WD Red Pro, 1x 3TB WD Red (both basic setup) - Digibit R1 Sat-IP-Server with SatIP-Axe-Firmware
OMV-Server-SW: Debian Buster with Proxmox kernel (always up-to-date), OMV v5 (always latest), omv-extras-plugin (always latests), AutoShutdown-Plugin, Docker with PlexMediaServer, TVHeadend, any many more
BackupServer: Synology DS1010+ with 4GB Ram, 9TB@SHR (different hdd’s), DSM 5.2-5967-2