Public Wi‑Fi is everywhere: airports, cafés, hotels, trains and planes. It’s convenient and often free—but it also introduces real risks that most travellers don’t see. Attackers can spoof hotspots, tamper with logins via captive portals, or downgrade your secure connections. Meanwhile, your mobile data connection is generally encrypted end‑to‑end by your operator and harder to meddle with. This guide explains the practical trade‑offs so you can make quick, confident decisions on the road. You’ll learn how captive portals work, what SSL stripping looks like in 2025, how to spot fake hotspots, and the exact settings to toggle before you connect. We’ll finish with a simple decision tree and safer defaults using eSIM, so you stay online without gambling with your banking, email or client data. If “public wifi safety” is your concern, this is your one‑stop, traveller‑first checklist.
The quick answer: when to use mobile data vs public Wi‑Fi
Use this 30‑second decision tree.
- Do you need to log in to banking, payments, email admin, cloud consoles, or handle work credentials?
- Yes → Use mobile data/eSIM. Avoid public Wi‑Fi.
- No → Continue.
- Is the Wi‑Fi network name verified with staff or signage, and protected by a password (WPA2/WPA3)?
- No → Use mobile data/eSIM.
- Yes → Continue.
- Are you forced through a captive portal (web page that asks you to accept terms, add email/room number)?
- Yes → Connect only to accept terms, then immediately enable your VPN before doing anything sensitive—or prefer mobile data.
- No → Continue.
- Are you seeing any certificate warnings, HTTP-only pages, or “Not secure” indicators?
- Yes → Disconnect and use mobile data/eSIM.
- No → Low risk—proceed for casual browsing/streaming.
Pro tip: If you’re in any doubt, default to mobile data or an eSIM travel plan. It’s the safest baseline.
How public Wi‑Fi actually works (and where it breaks)
Captive portals: convenience with a catch
Most public networks use captive portals: you connect, your first web request is intercepted, and you’re redirected to a sign‑in/terms page. This interception happens before encryption to the wider internet starts. Risks: - Phishing: Fake portals mimicking a venue’s page to capture email, passwords or card details. - Tracking: Your device’s MAC address and browser fingerprint may be logged. - Forced insecure requests: Some portals push you through HTTP before you can enable a VPN.
What to do: Confirm the network name with staff, use a throwaway email if required, and switch on your VPN the moment the portal grants access.
SSL stripping and downgrade tricks
Modern sites use HTTPS with HSTS (HTTP Strict Transport Security). Attackers on open Wi‑Fi may attempt to: - Block HTTPS upgrades, keeping you on HTTP. - Inject a look‑alike page before a secure session starts. - Present bogus certificates hoping you’ll click “Continue”.
Your defence: Never ignore certificate warnings. Use a browser with HTTPS‑only mode. Prefer apps with certificate pinning (many banking apps do this and will refuse unsafe connections).
Fake hotspots (“evil twins”)
Attackers clone a network name like “Airport_Free_WiFi” and broadcast stronger signal. If your device auto‑joins based on name alone, you’re connected to them. They can see and tamper with unencrypted traffic, and attempt man‑in‑the‑middle on poorly configured apps.
Defence: Disable auto‑join for public networks, verify the exact SSID with staff, and “Forget” networks after use.
Public Wi‑Fi vs mobile data: the real‑world risk difference
- Mobile data/eSIM: Your traffic rides an encrypted channel within the mobile network. While sophisticated threats (e.g., IMSI catchers) exist, they’re rare and targeted. For travellers, mobile data is significantly safer than open Wi‑Fi for logins and payments.
- Public Wi‑Fi: Shared medium, easy to spoof, and often funnels you through captive portals where interception is simplest. Hotels and conferences are common targets.
Bottom line: Default to mobile data/eSIM for anything sensitive. Use public Wi‑Fi for low‑risk browsing and downloads only when you’ve verified the network and hardened your device.
Safer connectivity with eSIM when you travel
A local or regional eSIM gives you affordable mobile data without hunting for risky Wi‑Fi. With Simology, you can browse plans by country or region via Destinations. Popular picks: - USA city breaks and road trips: Esim United States or broader Esim North America - Euro adventures: Esim France, Esim Italy, Esim Spain or multi‑country Esim Western Europe
For teams, zero‑drama travel data beats hotel Wi‑Fi every time—see For Business. Travel suppliers and venues can explore safer guest connectivity via our Partner Hub.
Before you connect: a quick hardening checklist
Do these once, then you’re covered trip‑wide.
- Turn on automatic updates for your OS, browser and key apps.
- Enable HTTPS‑Only/Always‑On in your browser.
- Install and configure a reputable VPN. Set “connect on untrusted Wi‑Fi.”
- Disable auto‑join for open networks; remove old public SSIDs.
- Turn off file sharing, printer sharing, and AirDrop/Nearby Share to “Contacts only” or Off.
- Use a passcode/biometrics and full‑disk encryption (default on modern devices).
- Prefer app‑based 2FA (not SMS) for important logins.
Pro tip: Add your eSIM before you travel so you land connected—no need to touch airport Wi‑Fi.
Connecting to public Wi‑Fi: step‑by‑step
- Verify the exact network name and whether a password is required.
- Turn off auto‑join for that network (so you connect consciously each time).
- Connect and load the captive portal. Provide only minimal info—avoid reusing important passwords.
- Once online, immediately enable your VPN before opening any other app or site.
- Check your browser shows the padlock/HTTPS on sites you visit. If you see a warning, stop.
- Keep sessions short. When you’re done, “Forget” the network.
Pro tip: If a venue offers a WPA2/WPA3 password, prefer it over truly open networks—there’s at least basic encryption between your device and the hotspot.
Spotting common attack patterns on public Wi‑Fi
- Portal phishing: The sign‑in page asks for your email and password for a third‑party service (e.g., “Sign in with your email provider”). Don’t. Portals should never need those credentials.
- SSL warnings: “Your connection is not private” pop‑ups. Never click through—disconnect.
- Name games: Multiple similar SSIDs (FreeAirportWiFi, Airport_Free_WiFi, AirportWiFi‑Guest). Ask staff which is real.
- Rogue DNS: You type a familiar address and land on an odd‑looking site. Quit immediately; recheck with mobile data.
- Sudden certificate prompts in apps that never ask for them (email, messaging). Treat as a red flag.
When a VPN helps—and when it can’t
- Helps with: Encrypting your traffic across the local Wi‑Fi so others can’t sniff it; bypassing rogue DNS; reducing hijacking risk.
- Limitations: You usually must connect to the hotspot (and often its captive portal) before the VPN can start. A compromised device or phishing page can still trick you before the VPN is active.
- Practical tip: Connect → complete the portal with minimal info → enable VPN immediately → proceed. If the VPN won’t connect or drops repeatedly, switch to mobile data.
Venue‑by‑venue: what to expect
- Airports and trains: High‑volume, prime targets for spoofed SSIDs. Treat as untrusted; prefer mobile data.
- Hotels: Portals tied to room numbers or surnames are common, but networks are shared across floors. Use VPN; avoid admin logins.
- Cafés and bars: SSIDs frequently change; lots of clones around. Verify the name at the till.
- Conferences: Attackers love events. Expect evil‑twin networks. Use mobile data for anything sensitive.
- In‑flight Wi‑Fi: Often proxied and filtered. Fine for casual use, but not for banking or work admin.
Quick device hardening checklist (phones and laptops)
- Disable Wi‑Fi when you’re not using it; rely on mobile data/eSIM.
- Use a privacy‑focused DNS provider within your VPN, or set encrypted DNS (DoH/DoT) in system settings if supported.
- Limit sensitive notifications on lock screen.
- Use separate browser profiles: one for travel, one for personal.
- Log out of sessions you don’t need; clear site data after public Wi‑Fi sessions.
- For work devices, stick to your organisation’s managed VPN and policies.
Pro tip: If your work depends on reliable, safe connectivity, standardise on eSIM data and keep Wi‑Fi as a last resort.
Simple “safer by default” plan for travellers
- Before you fly: Add a local or regional eSIM from Destinations.
- On the ground: Use mobile data for logins, bookings and payments.
- Only use public Wi‑Fi for downloads or streaming you don’t mind being interrupted.
- Keep your VPN ready for those moments where Wi‑Fi is unavoidable.
- Forget networks after use; don’t auto‑join anything public.
FAQ: Public Wi‑Fi vs mobile data
- Is public Wi‑Fi safe if the site shows HTTPS?
- Safer, but not safe by default. HTTPS protects the connection to that site, but portals, DNS tampering and fake certificates can still bite. Always heed warnings and prefer a VPN.
- Is mobile data always safer?
- For most travellers, yes. Mobile networks encrypt traffic at the radio layer and are harder to spoof casually. It’s the better choice for banking, email and bookings.
- Should I use a VPN on public Wi‑Fi?
- Yes. Use a reputable VPN and enable it immediately after the captive portal. If it won’t connect reliably, switch to mobile data.
- Can I do mobile banking on hotel Wi‑Fi?
- Best practice: use mobile data/eSIM for banking. If you must use Wi‑Fi, use your banking app (which likely pins certificates), turn on your VPN, and double‑check for any warnings.
- How do I tell if a hotspot is fake?
- Verify the exact network name with staff; beware multiple look‑alike names; check signal strength anomalies; avoid previously saved “free” SSIDs; and prefer password‑protected Wi‑Fi.
- Do I need an eSIM if venues offer free Wi‑Fi?
- If you value reliability and security, yes. An eSIM keeps you online for sensitive tasks without relying on unknown networks. Explore country and regional options via Esim United States, Esim France, Esim Italy, Esim Spain and Esim Western Europe, or go broader with Esim North America.
Next step: Choose a safe, local data plan before you travel—browse Destinations and add your eSIM in minutes.