Connecting the ReminderPrint App to Your Server

Before You Start

Make sure you have:

• The ReminderPrint print server running on your Raspberry Pi

• Your Server URL — either your local network address or Tailscale IP

• Your API Key — generated during the server setup process

Step 1 — Open Printer Settings

Open the ReminderPrint app and tap the printer status indicator in the top right corner of the main screen. This opens the Printer settings screen.

Step 2 — Enter Your Server URL

Under the Connection section, tap Server URL and enter your server address.

On your home network:

http://printserver.local:8000 

From anywhere (using Tailscale):

http://100.x.x.x:8000 

Replace 100.x.x.x with your Pi's Tailscale IP address, which you can find by running tailscale ip -4 on the Pi.

Note: Make sure to use http:// not https://. The print server does not use SSL by default.

Tap Done to save.

Step 3 — Enter Your API Key

Back in the Connection section, tap the API Key field and enter the key that was generated during your server setup.

If you have lost your API key, you can find it on the Pi by running:

sudo systemctl cat printserver | grep API_KEY 

Step 4 — Test the Connection

Tap Reconnect Printer at the bottom of the settings screen. If everything is configured correctly, the status indicator will turn yellow and show Printer Connected.

If it stays red, see the troubleshooting section below.

Printing Your First Reminder

Once connected, head back to the main screen. Write your reminder in the slip, set a due time if needed, and tap Print. Your receipt printer should produce a formatted reminder within a few seconds.

Connecting from Outside Your Home Network

To print from anywhere — not just your home WiFi — you need Tailscale running on both your Raspberry Pi and your iPhone.

1. Install the Tailscale app on your iPhone from the App Store

2. Sign in with the same Tailscale account you used on the Pi

3. Enable the VPN toggle in the Tailscale app

4. In ReminderPrint, set your Server URL to your Pi's Tailscale IP (http://100.x.x.x:8000)

Once Tailscale is active on your phone, ReminderPrint can reach your printer from anywhere in the world.

Troubleshooting

Printer shows as Offline after tapping Reconnect

• Check that the print server is running on the Pi: sudo systemctl status printserver

• Confirm your Server URL is correct and includes the port (:8000)

• Make sure you are using http:// not https://

• If connecting via Tailscale, ensure the Tailscale VPN is active on your iPhone

Connection works on WiFi but not away from home

• Open the Tailscale app on your iPhone and check the VPN toggle is on

• Confirm Tailscale is running on the Pi: sudo systemctl status tailscaled

• Use your Tailscale IP address in the Server URL, not printserver.local

API key rejected (Unauthorized error)

• Double check the key entered in the app matches exactly what is set on the server

• Keys are case-sensitive — make sure there are no extra spaces

Reminder sent but nothing prints

• Check the printer is powered on and paper is loaded

• Look at the server logs for errors: sudo journalctl -u printserver -f

• Try a test print directly from the Pi using the curl command in the setup guide