Contents
Testing an app or a website on a real French mobile network
CGNAT, IPv6, connections cut by the carrier: what a mobile network changes for your app or site, and how to reproduce it from your office.
update Updated
Teams test on the office Wi-Fi. Their users, on the other hand, are on 4G/5G, behind a carrier that does not behave like a home router. Some failures only exist there, and they cannot be seen from the office.
What the mobile network changes
One IPv4 address for hundreds of subscribers. Mobile carriers share the same public IPv4 address among many customers (CGNAT). If your service limits the number of requests per address, or blocks an address after failed logins, you block at once hundreds of users who did nothing. See Collective punishment.
IPv6. French carriers widely hand out IPv6 on mobile. Does your backend accept it everywhere? Database columns sized for an IPv4, address allowlists, logs and anti-fraud tools are where it breaks.
IPv6-only networks. Some mobile networks only provide IPv6 and translate to IPv4 (NAT64, 464XLAT). An IPv4 address hard-coded in an app can fail there. Apple, for that matter, has long required App Store apps to work on an IPv6-only network.
Idle connections cut. Carriers close NAT mappings that stay silent. A WebSocket or a long-lived connection without keepalive messages can die silently, with no error on the server side.
Approximate geolocation. Geolocation databases often place a mobile address in Paris or in the carrier's region. If your service adapts its content to the city, test what it does with a misplaced address.
Reproducing it from the office
| Method | What it tests | Setup |
|---|---|---|
| Browser set to the proxy | The site, over HTTP and HTTPS | Chrome and Firefox |
| Test phone set to the proxy | The app, for the traffic that honors the proxy | Android and iPhone |
| WireGuard tunnel on the phone | Everything, UDP and HTTP/3 included | WireGuard tunnel |
The tunnel is the most faithful method: many apps ignore the system proxy, and the tunnel leaves them no choice.
Choosing the carrier and the IP mode
Carriers do not all behave the same: some rewrite or terminate TCP connections along the way, others let them through intact. To reproduce a bug reported by subscribers of a specific carrier, test on that carrier; contact us if you want a particular one.
The Premium plan (phone exit) lets you choose between IPv4 only, dual stack or IPv6 only: enough to test all three cases without changing hardware. The Complete plan goes out over IPv4.
What a proxy does not test
Ranking in the app stores. The App Store and Play Store country depends on the account, not on the IP address. Changing IP does not change the results shown.
Radio quality. The proxy goes out through a real 4G/5G line, but your test also goes through your own connection up to us. To measure coverage or radio latency, you need a phone in the field.
FAQ
Can I automate these tests?
Yes: the proxy works in Playwright, Puppeteer or any HTTP client. See AI agents and automated browsers.
Why not a network emulator?
It simulates latency and packet loss, and that is very useful. It simulates neither CGNAT, nor IPv6 translation, nor a real carrier's equipment. The two complement each other.
See also: What is a mobile proxy? · Testing your proxy
Need a French mobile proxy? A real French 4G/5G line, one HTTP port and one SOCKS5 port, IP rotation on demand.
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