Work through the steps in order. Most printing problems are a network or printer-location issue.
Step 1: Is anything stuck?
If Nomni POS cannot send an order to a printer, the printer icon lights up with the number of banked print tasks. Fix the printer, then resume the jobs in Printing Tasks. The icon does not light up if printing was never set up, for example if no printer location is set for the product.
Step 2: Basic checks (all models)
Paper roll loaded and not empty. Epson TM-82II uses 80mm rolls, feeding from the bottom up.
Power on. The network cable is firmly seated at both the printer and the router or switch.
The printer and iPad are on the same network (SSID) and on the same subnet (192.168.9.xxx).
On the iPad: Settings > Wi-Fi > (i), set Private Wi-Fi Address OFF and Limit IP Address Tracking OFF. Settings > Nomni POS, set Local Network ON.
Restart the printer, then the iPad.
Step 3: Check the printer in Nomni POS (on the Master)
Open the Printer List. The printer should have a green tick (discovered) and its switch toggled on (blue).
Tap the gear icon, then PRINT. If you get a test print, the connection works.
Tick the right printer location(s) for this printer.
Check the printing settings for your workflow: C1 Print order docket upon payment complete, C3 Print order docket upon hold order, C13 Print transfer notice, C14 Print cancel notice, C29 Print production docket from current device.
Step 4: Only some items don't print
Each product prints where its printer location is set. In the backend, check Print Settings > Printer Locations, and that the product has the right location. If you have more than one printer, every product must have a location or its dockets will not print.
If you're on EMS, try to tap and hold on the product on your POS and see if it has the correct printer location.
After changing printing locations, sync.
Step 5: Model-specific checks
Epson (e.g. TM-82II)
Blank dockets: use 80mm rolls and check the roll direction.
Yellow LED off or blinking = network problem. Restart the router and printer, reseat (unplug-plug back) the cable, then test print.
Print a configuration or self-test page by turning the printer off, hold the feed button, turn it on and keep holding until it beeps. to see the printer's IP address.
Star (e.g. SP712)
Print the configuration: turn the printer off, hold the feed button, turn it on and keep holding until it beeps.
IP address conflict (Epson and Star)
Print the configuration page from each printer and compare the IP addresses.
If two match, open Safari on the iPad and go to the printer's IP address (typing the IP address of your printer on the Safari browser), then TCP/IP settings.
Change only the last number to one no other printer uses, and save.
In Nomni POS, refresh the printer list, connect to the new listing (tick), assign its printer locations and delete the old listing (cross).
Zebra label printers (e.g. ZD410)
Labels misaligned or skipping: run the printer's media calibration.
Hot or cold drink labels not printing: check that the drink products are assigned to the label printer's printer location
Step 6: Two dockets printing for one order
This usually means two printer locations point at the same printer, or a product has two locations. Check Printer Locations and the product's location.
Still not working?
Contact support with your store name or ID, the printer model, what the printer lights show, and whether the test print works. Please don't factory reset your router/printer.
Related: Printer Troubleshooting · Printer Locations · Epson TM-82II Troubleshooting · How can I troubleshoot and resolve printer disconnection issues on the Nomni POS system?