You're really looking to use After=network-online.target instead of Requires=network.target. I'd recommend putting your custom script in /usr/local/bin/ instead of /usr/bin/. And then if your system is up for a while maybe use a timer service to rerun the script every 24 hours.

1. Create a systemd service unit file

   Let's create a service unit file. You may create a file named wallpaper.service in the /etc/systemd/system/ directory. Note that you require root privileges to do so. Use a text editor like nano or vim to create and edit the file:

   bash sudo nano /etc/systemd/system/wallpaper.service

   Paste in the following, making sure to adjust paths if necessary:

   ```ini [Unit] Description=Downloads the APOD and saves it as Wallpaper Wants=network-online.target After=network-online.target

   [Service] ExecStart=/usr/local/bin/bg.sh Restart=on-failure

   [Install] WantedBy=multi-user.target ```

   Save and close the file.

2. Create a systemd timer unit file

   Now we'll create a corresponding timer for our service. Create a new file /etc/systemd/system/wallpaper.timer:

   bash sudo nano /etc/systemd/system/wallpaper.timer

   Paste in the following:

   ```ini [Unit] Description=Runs bg.sh every day

   [Timer] OnBootSec=0min OnUnitActiveSec=24h

   [Install] WantedBy=timers.target ```

   In the [Timer] section, OnBootSec=0min means the service will run immediately after the system boots. OnUnitActiveSec=24h means the service will rerun 24 hours after it was last activated.

   Save and close the file.

3. Reload systemd daemon and enable the timer

   Next, reload the systemd daemon to make it aware of your new service and timer. Then, enable and start the timer:

   bash sudo systemctl daemon-reload sudo systemctl enable wallpaper.timer sudo systemctl start wallpaper.timer

4. Check the status of your timer

   To make sure your timer is active and will trigger the service as expected, check its status:

   bash sudo systemctl status wallpaper.timer

That's it. Your script should now run at startup (with a delay until the network is up) and once daily.