Connect a thermal printer to your laptop: LAN, Wi-Fi or USB.

Look at the ports on the back of the printer, then read across. The first three columns hold whatever billing software you run. The last two are about EasyKOT, and they say what is true today rather than what would look good.

Our advice: a LAN cable or USB at the counter. On both, the Desktop App watches the printer for you and no router setting can get in the way. If the printer is meant to live with an Android phone, read pairing a Bluetooth printer with an Android phone instead.

In EasyKOT: LAN and Wi-Fi are both Network (Wi-Fi / Ethernet), USB is its own choice, and Bluetooth sits under Serial / Bluetooth. Type a public address by mistake and the Desktop App refuses it: a printer has to be on the store's own network. That is a safety rail, not a bug.

Print the printer's own status page: hold the feed button while you switch it on. The slip shows its IP address, and usually its MAC address too. Then check the laptop's address: ipconfig in Command Prompt on Windows, or System Settings → Wi-Fi → Details on a Mac.

The rule is short: the first three numbers of both addresses must match. 192.168.1.20 and 192.168.1.87 are on the same network; 192.168.1.20 and 192.168.123.100 are not. That is the whole check.

They don't match? Move the printer onto your network, once

1. Plug the printer into the router with a LAN cable. For makers like Rongta and Xprinter the wizard's tip says the same: cable first.
2. For a few minutes, give the laptop an address in the printer's range with a different last number: printer on 192.168.123.100, laptop on 192.168.123.50, subnet 255.255.255.0. On Windows: Settings → Network & internet → Wi-Fi or Ethernet → IP assignment → Edit → Manual. On a Mac: System Settings → Network → Details → TCP/IP → Configure IPv4: Manually.
3. Open the printer's address in a browser, for example http://192.168.123.100. Many network printers show their settings page there. Some makers use a small setup program over USB instead: check the disc in the box or the maker's site.
4. Enter an address on your own network (the router's first three numbers, then a free last number such as .200), or switch DHCP on so the router hands one out. Save; the printer restarts.
5. Set the laptop back to Automatic (DHCP). Print the status page again and check the new address.

In EasyKOT: pick the brand in the wizard and Detect tries that maker's factory address first. If the printer is still on it when setup finishes, the Desktop App says “Still on its factory address”: it works today, but a second printer of the same make would collide with it, so move it when you have a minute.

These are facts about how the printers leave the factory, not a list of supported printers. They are the four tips the Desktop App's wizard shows. ESC/POS alone is not a support guarantee; test the exact model and interface with both a test slip and a sample bill.

Models vary. Your printer's own status page is the final word.

A router lends each device an address; it does not give it one for keeps. After a power cut or a router restart the printer can come back on a different address, and every Desktop App looking at the old one sees it Offline. A reservation pins it. Two minutes now saves a bad evening later.

1. Find the sticker under or behind the router. It has the admin page's address (often 192.168.1.1 or 192.168.0.1), a username and a password.
2. On the same Wi-Fi, open that address in a browser and log in.
3. Under DHCP or LAN settings, find the option. Routers name it differently: DHCP Reservation, Address Reservation, Static Lease or DHCP Binding.
4. Pick the printer by its MAC address (it is on the status page) and give it the IP it has now.
5. Save. Switch the printer off and on, and check the address on its status page.

Some internet providers' routers hide this option or leave it out. Then set a fixed (static) IP on the printer's own settings page instead, using a number outside the router's DHCP range.

In EasyKOT: after the first good connection the Desktop App remembers the printer by its hardware address, and when the address moves it goes looking there first. The wizard's closing “Keep this address” note points you at this reservation all the same, because it is the surer fix. Still Offline? Read printer Offline after a router restart.

The generic part first. Not every USB cable carries data: some only charge, and they look identical, so use the cable that came with the printer. On Windows, a maker's driver sometimes holds the port, and then no program can open the printer.

In EasyKOT, run Detect printers with the cable plugged in and the vendor id and product id fill themselves in, because a USB printer says what it is. There is no driver to install for EasyKOT; on Windows the built-in USB printing driver is enough.

Settings → Printers & KDS → Add manually, on USB.

Detect does not list it at all? Read USB printer not found: the cable, the driver, and the Windows fallback.

Live status: the Desktop App checks a USB printer in the background, just like a network one. A cheap printer that never answers status questions reads Can't verify — will still try to print, which is honest rather than a false green. For those, the test slip is the real check, so print one before the rush.

Both live behind one choice, Serial / Bluetooth, because a Bluetooth printer paired in your operating system's Bluetooth settings appears to the laptop as a serial port. Pair it there first; then it shows up here.

Settings → Printers & KDS → Add manually, on Serial / Bluetooth.

• The port path. On a Mac it starts with /dev/cu.; on Windows it is a COM number, usually COM3.
• Baud rate is for wired serial only. 9600 suits most; some models want 19200, 38400 or 115200, and the printer's self-test slip tells you. For Bluetooth the field is ignored.
• No live status. The Desktop App asks a serial or Bluetooth printer how it is only when you press Check printer or Test connection. Asking in the background would fight the print queue for the same port, so it deliberately does not.
• The honest part. We have no record yet of a healthy Bluetooth print from a laptop. On a Mac a Bluetooth link can stall; the Desktop App gives up after 10 seconds with an error instead of hanging. For the counter, use LAN or USB.
• Paired but nothing prints? Bluetooth printer paired but not printing. Printing from a phone is a different job: the Android phone guide.

If the printer is already installed as a normal printer on your computer, EasyKOT can send bills through that queue instead of talking to it directly. On Windows the connection is labelled Windows printer (driver queue — no live status); on Mac and Linux it is System printer (OS driver). Jobs go through CUPS on Mac and Linux or the Windows spooler on Windows. On this path the Desktop App can only tell whether the queue exists; it cannot read paper-out or cover-open back.

• Type the queue name exactly as your OS shows it. On Windows that is the name in Printers & scanners; on a Mac, the name in System Settings → Printers.
• Prefer Network or USB when you have the choice. Both give the Desktop App live status. System printer is the right call when a printer is already wired into the OS and you would rather not touch it.
• The Windows spooler path has not been through our hardware runbook yet, so there too the test print is the real check.

• The printed area is narrower than the roll. About 72 mm on an 80 mm roll and about 48 mm on a 58 mm roll; the exact figure varies by model.
• On 80 mm, EasyKOT prints 42 characters a line. Long dish names, portion labels and the GST split all fit without wrapping. This is the counter default. Some 80 mm printers fit 48: choose 80mm wide for those, and if its 48-digit test row wraps, your printer is a 42 and 80mm is the right pick.
• On 58 mm, 32. Cheaper rolls, sold in every stationery shop, and perfectly fine for a short menu or a takeaway counter, as long as the setting matches.
• The test slip catches a wrong guess. It prints a row of digits exactly as wide as the size you chose: 42 for 80 mm, 32 for 58 mm. Choose 80 mm on a 58 mm roll and the row wraps, and the slip says so: “If the digits wrapped onto a second line, choose 58mm in Settings > Printers & KDS.” Choose 58 mm on 80 mm paper and you get a wide blank margin on the right, with the slip telling you to choose 80mm. The paper tells you before a customer sees a wrong bill.
• Money prints as “Rs.”, on purpose. The ₹ sign is missing from the character sets thermal printers ship with, so a printed bill reads Rs. 480.00. On screen it is still ₹.

Still choosing a printer? The thermal printer buying guide covers 58 vs 80 mm and what to look for.

Every saved printer has a Role, and there are three: Both, Receipt and Kitchen (KOT). One printer on the counter set to Both runs an entire small restaurant.

• Receipt takes the customer bill, the reprints and the cash-drawer kick.
• Kitchen (KOT) takes the kitchen tickets. With no kitchen printer set up, KOTs go to a printer marked Both, and failing that to the receipt printer: the kitchen never silently misses a ticket.
• A second printer for the kitchen is the natural next step: set up the kitchen KOT printer and the cash drawer. A kitchen across the building is where a LAN cable earns its keep.
• Drinks and food on separate paper? Set up kitchen stations once your first two printers are running.
• Two Desktop Apps in one store? Add a second Desktop App.
• The cash drawer is not a separate device. It plugs into the receipt printer's DK port, and the Cash drawer pin setting on the form picks which pin fires it.

Every saved printer's row has a Check printer button. It asks the five questions a support call would and answers them itself: can the Desktop App reach it, is the cover shut, does it speak ESC/POS, is it healthy, and does a test slip come out. Each step ends Pass, Needs attention, Unsupported (this printer just doesn't say) or Not tested.

Settings → Printers & KDS → Check printer: a healthy printer, five for five.

• The first thing that needs attention gets its fix. A card names the likely cause and the first thing to try, plus a QR code that opens the matching easykot.com guide on a phone.
• Share report copies plain text: the printer, its connection, the five results and the guide link, ready to paste into WhatsApp. It never includes what was on a ticket or a bill.
• Unsupported is not a failure. Plenty of inexpensive printers never answer status questions; they still print every ticket, and the test slip is the check for them.

Almost every case is one of three: paper loaded the wrong way up, the printer not actually powered, or the laptop on a different network from the printer. Then run Check printer; it usually names the exact one.

• Thermal printer not printing: every symptom, fixed in order
• Nothing finds the printer, even by IP (the router keeps devices apart)
• Every printer unreachable on a Mac: the Local Network permission

The important part first, though: the sale is already saved. EasyKOT writes the bill to the laptop before it queues the print, and a failed ticket retries by itself (1, 2, 5, 15, 30 and 60 seconds, then every minute) for up to 5 minutes before it asks a person for help. You can also read how the Desktop App's print queue and reprints work.