Fehlermeldung beim aktivieren des Docker Repo

Failed to execute command 'export PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin; export LANG=C; omv-mkconf omvextras 2>&1' with exit code '2': Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --homedir /tmp/tmp.CFRJfBlLyM --no-auto-check-trustdb --trust-model always --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --keyring /etc/apt/trusted.gpg.d/debian-archive-jessie-automatic.gpg --keyring /etc/apt/trusted.gpg.d/debian-archive-jessie-security-automatic.gpg --keyring /etc/apt/trusted.gpg.d/debian-archive-jessie-stable.gpg --keyring /etc/apt/trusted.gpg.d/debian-archive-stretch-automatic.gpg --keyring /etc/apt/trusted.gpg.d/debian-archive-stretch-security-automatic.gpg --keyring /etc/apt/trusted.gpg.d/debian-archive-stretch-stable.gpg --keyring /etc/apt/trusted.gpg.d/debian-archive-wheezy-automatic.gpg --keyring /etc/apt/trusted.gpg.d/debian-archive-wheezy-stable.gpg --keyring /etc/apt/trusted.gpg.d/openmediavault-archive-keyring.gpg --keyring /etc/apt/trusted.gpg.d/openmediavault-keyring.gpg --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 58118e89f3a912897c070adbf76221572c52609d gpg: requesting key 2C52609D from hkp server keyserver.ubuntu.com ?: keyserver.ubuntu.com: Host not found gpgkeys: HTTP fetch error 7: couldn't connect: Connection refused gpg: no valid OpenPGP data found. gpg: Total number processed: 0