It seems that the usual way of mounting remote file systems that is based on fstab(5) does not work anymore on modern Debian GNU/Linux systems in their default configuration.
The culprit is systemd(1): by the time the service will try to mount a remote file system, the machine most probably will not be online yet and mount(8) will fail.
Debian does not seem to offer any other solution but to use systemd-networkd(8) together with systemd-networkd-wait-online(8).
First, configure systemd-networkd(8).
WARNING: You should like to modify the below to fit your purpose. At very least, you should replace enp0s25 with the correct name of an existing network interface. For a coherent guide, please see the ArchWiki:
sudo tail /etc/systemd/network/50-default.network <<EOF [Match] Name=enp0s25 [Network] DHCP=yes EOF
Next, enable systemd-networkd.service and systemd-networkd-wait-online.service:
sudo systemctl enable systemd-networkd sudo systemctl enable systemd-networkd-wait-online
At this point, I recommend to reboot and check connectivity in order to eliminate any confusion regarding the cause of a possible mistake at a later stage.
Upon reboot, you can proceed to configuring the mount point in fstab(5).
For instance, I have the following in fstab(5) of a Debian machine in order to mount a read-only remote mount point that is served by nfsd(8) running on OpenBSD:
192.168.123.237:/home/export /mnt/nfs nfs resvport,ro,rsize=32768,wsize=32768
(Please note that the above does not require any options provided by systemd-mount(5).)
Vadim Penzin, August 8th, 2019
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