POS Troubleshooting
Common issues and solutions for Synalux POS.
Orders not appearing on KDS
Symptoms: Order placed on register but doesn't show on Kitchen Display.
Solutions:
Verify the KDS station is assigned to the correct menu categories in Settings → KDS Stations
Check that the KDS browser tab is connected — look for the green "Connected" indicator
Confirm both devices are on the same network
Hard-refresh the KDS page (Ctrl+Shift+R or Cmd+Shift+R)
Receipt printer not printing
Symptoms: Orders go through but no receipt prints.
Solutions:
Check USB/Bluetooth connection — unplug and reconnect
Verify printer is selected in Settings → Hardware → Receipt Printer
Test with "Print Test Page" in printer settings
For Bluetooth printers: forget and re-pair the device
Check paper roll — thermal printers fail silently when empty
Payment processing errors
Symptoms: "Payment failed" or "Connection timeout" at checkout.
Solutions:
Verify internet connection — POS needs connectivity for payment processing
Check that your payment processor credentials are current in Settings → Payments
For terminal-based payments: restart the payment terminal
If using Shift4: verify the auth token hasn't expired in the integration settings
Try a smaller test amount ($0.50) to isolate the issue
Offline mode — orders not syncing
Symptoms: Orders taken offline aren't appearing in reports after reconnecting.
Solutions:
Keep the POS tab open after reconnecting — sync happens automatically
Check the sync indicator in the top bar — it should show "Syncing..." then "Synced"
Do NOT clear browser data while orders are pending — this deletes the offline queue
If stuck: navigate to Settings → Advanced → Force Sync
Menu items showing wrong price
Solutions:
Check the item price in Menu Builder — prices are per-item, not per-category
If using modifiers with price adjustments, verify the modifier group pricing
Clear browser cache after price changes (or wait for the next auto-refresh cycle)
Check for active discount rules in Settings → Discounts that may be auto-applying
Staff can't log in with PIN
Solutions:
Verify the PIN is set in Staff → [Employee] → PIN
Check that the employee's role has "Register Access" permission
Ensure the employee is assigned to the current location (multi-location setups)
Try resetting the PIN — PINs must be exactly 4 digits
Online ordering QR code not working
Solutions:
Verify online ordering is enabled in Settings → Online Ordering
Check the QR code links to the correct URL (scan it yourself first)
Ensure the menu has at least one published category with items
For table QR codes: verify table numbers match between floor plan and QR generation