He had entered a wrong parameter. Now his router was closer to being a brick.

Alex was a digital nomad who lived out of a backpack. For two years, his trusted companion was a rugged, white ZTE MF286 4G router. It had served him well, converting a local SIM card into a private Wi-Fi bubble in cafes from Bangkok to Barcelona.

Alex was excited. This was genuine hacking. He spent an afternoon downloading drivers, installing terminal software, and carefully typing commands. The router beeped, flashed… and then showed a

One site looked slick. It asked for his IMEI (the router’s unique serial number, found under the battery or on a sticker). Alex typed it in. The page whirred… then demanded: “Complete one survey to generate code.”

One popular “free” method involved using via a USB cable. A user posted: “Connect router to PC, open PuTTY, send AT+ZNCK=1,2, ...”

“You want free?” Mr. Binh said. “I give you free advice.”