The short answer
Open the QR generator, switch to the Wi-Fi tab, and fill in three things: the network name (SSID), the encryption type, and the password. If the router hides its network name, tick the hidden-network option too, then download the PNG. Three traps to head off. Passwords containing <code>;</code> <code>:</code> <code>"</code> <code>,</code> or <code>\</code> must be escaped or the scan simply will not connect — the tool handles this for you, but check it if you hand-write the format. Choose <strong>WPA</strong> rather than WEP or "no password", and make sure you are reading the guest network's credentials, not the main one. Do not print smaller than 2 cm; beyond a metre of reading distance you want 4 cm or more. And before anything goes on a wall: change the default password.
What the three fields mean
A WiFi QR code is really just a string in an agreed format that the phone camera hands to the operating system to parse. The common WPA form looks like this: <code>WIFI:T:WPA;S:network;P:password;H:false;;</code> — <code>T</code> is the encryption type, <code>S</code> the network name, <code>P</code> the password, <code>H</code> whether the network is hidden, and the trailing semicolon is required. When filling the form, the network name must match your phone's WiFi list <strong>exactly</strong> — case, stray spaces, and which band of a dual-band router you are on all matter. Pick the encryption type that matches the router configuration (almost always WPA). Tick the hidden option only when SSID broadcast is genuinely off, because a wrong tick produces a scan that finds no network at all. The tool exposes these as separate fields precisely so you never have to assemble the string by hand.
Special characters in the password: the usual reason a code fails
This is the classic WiFi QR code trap. Fields in the format are separated by semicolons, so a password containing <code>;</code>, <code>:</code>, <code>"</code>, <code>,</code> or <code>\</code> must be escaped with a backslash: the semicolon becomes <code>;</code> and a literal backslash becomes <code>\</code>. Modern routers hand out passwords mixing upper and lower case, digits and symbols, so the odds of hitting one of those five characters are not low. The symptom is a scan that reports "cannot connect" or shows nothing, while typing the same password by hand works fine — manual entry takes a different path and does no format parsing. Using the tool, none of this is your problem. The one case worth caring about is when you copy a WiFi string from elsewhere and edit fields yourself: then check the escaping yourself.
Hidden networks and guest networks are different things
The two get mixed up constantly. A "hidden network" is one where the router does not broadcast its name, so a phone must add it manually before connecting — that is the only case where the hidden flag belongs. A "guest network" is a separate isolated network with its own password and often its own name (many routers append "Guest"). The card on your reception desk should point at the <strong>guest</strong> network. Guest networks are isolated from your smart devices, NAS and printers, so a guest who connects cannot reach your LAN; publishing the main network instead hands your whole local network to the room. So before printing, confirm exactly which network name and password you used — and note that guest networks ship disabled on many routers, so you may have to enable it and set a temporary password in the admin page first.
Print size and error correction: picking a trade-off
A WiFi QR code holds little data, but it only scans if it occupies enough pixels on screen. Rule of thumb: for a wall card read from within a metre, keep the physical side at <strong>2 cm or more</strong>; across a meeting table two or three metres away, go to <strong>4–5 cm</strong>; on a business card, in a page corner, or on packaging, 6 cm or more. Do not expect the printer's resolution to rescue a small code — once the fine module edges smear, no amount of error correction helps. Error-correction level (M / L / Q / H) governs how much of the pattern may be covered or soiled and still scan, so pick <strong>M</strong> or <strong>Q</strong> for ordinary printing and <strong>H</strong> when the code will sit on a busy background or where water and grease are likely. One more practical note: test with two different phones after printing. Camera tolerance varies noticeably between devices, especially older Android models.
Four things to do before it goes up
One, <strong>change the default password</strong>: the factory or carrier-issued password printed in a public place is the same as no password at all, so set something nobody can guess (most admin pages check strength). Two, <strong>limit clients or use the guest subnet</strong> where the router allows it. Three, <strong>rotate the password regularly</strong> — in guesthouses and shared offices a printed card stays valid for months, so change it monthly or quarterly. Four, <strong>reprint the card when you change the password</strong>: an outdated card that fails to connect is an embarrassing moment at the door. Treat these as one routine, not four separate chores.
想马上动手：用 二维码生成器 切到 Wi-Fi 标签填三个字段，门店要一次印几十张桌牌用 批量二维码生成 打包下载，码上要放 logo 或想先看看扫出来是什么内容，先用 编码识别 核对一遍文本格式。Try it now: switch to the Wi-Fi tab in the QR code generator and fill in the three fields; for dozens of table tents use bulk QR generation; if you want to verify the raw text before printing, run it through encoding detection first.
FAQ
The scan comes back blank or as noise.
Usually the code is too small or the contrast is too low. For print, take the side up to 2 cm or more and keep dark modules on a light background — dark code on dark paper, or a transparent-background watermark laid over a pattern, will not scan reliably. On a phone screen, raising brightness and nudging the angle usually fixes it.
It says the password is wrong, but the password is right.
Three possibilities. One: the password contains <code>;</code> <code>:</code> <code>"</code> <code>,</code> or <code>\</code> and the string was not escaped properly — by far the most common. Two: the encryption type is wrong (the router is WEP but you selected WPA, or you picked "no password"). Three: the network name does not match exactly, especially with dual-band routers sharing a name or a stray space. The tool avoids the first two automatically, so focus on the third — compare your phone's network list character by character.
It scans on my iPhone but not on Android (or the other way round).
WiFi QR parsing is an OS-level feature and implementations differ: newer phones handle it in the stock camera, while some models need the system's own scanning entry point, found in Settings or the negative-one screen depending on the OS version. Since some of that entry point lives in a control centre or a notification shade, the pragmatic advice for a public sign is to test on the two or three handset models your audience actually uses rather than only your own. Test before printing, not after the guests arrive.