Yes — installing downloads the profile from a server, so the phone has to be online. Wi-Fi is the usual way, and it is why installing at home before you fly is the recommended order
The QR code is not the eSIM. It is a set of instructions telling your phone where to fetch the profile, and fetching it needs a connection.
What Counts as a Connection
- Home, hotel or café Wi-Fi — the normal answer
- Mobile data on your existing SIM, if you have an allowance to spare
- A hotspot shared from another phone
Using your home SIM's data abroad to install means roaming charges from your own operator. If that is the only option, connect for the minute the download takes and switch roaming off again immediately.
After Installation
Once the profile is on the phone, no internet is needed again. It sits there whether the phone is online or not, and it connects on its own when you reach the destination — including with Wi-Fi switched off, which is the point.
Airport Wi-Fi is usually enough, but it is slow, crowded and sometimes behind a sign-in page. Installing the night before removes every one of those risks.
This is also why an eSIM cannot be installed in the air. Aircraft Wi-Fi is often too unreliable for the download — see Will My eSIM Work on a Cruise Ship or a Plane?
