Guest Wi-Fi QR codes without reprinting — Scanduro

Put the network name and password on a page you edit, so rotating the password leaves every printed placard correct. A join code sits on the page.

Guest Wi-Fi: either a static code that encodes the credentials, or a hosted Wi-Fi page showing network name and password plus a second join code, so rotating the password is an edit rather than a reprint. No browser can join a network from a web page, so the join is the second scan. No captive portal, vouchers or session data.