The bank verification code was somewhere between London and my phone, and the airport Wi-Fi had just replaced my travel eSIM as the active connection. Gmail stopped refreshing. WhatsApp showed one grey tick. The ride-hailing app was waiting for confirmation while the driver I had booked was already approaching the terminal. I blamed the eSIM, switched airplane mode on and off, and watched the signal return without the missing message.
I had landed in Shanghai with what seemed like the cleanest possible travel setup: one eSIM, installed before departure, with enough data for the whole trip.
That simplicity was part of the appeal. China’s expanded visa-free policies have brought more short-notice visitors, many arriving for a few days rather than staying long enough to build a complete local mobile setup. In the first half of 2026, visa-free entries by foreign nationals rose by more than 30 percent year on year. (RFC 9000)
I was exactly that kind of traveller.
The eSIM activated before the aircraft reached the gate. Messages arrived, maps loaded and the apps I normally used at home opened over cellular data. There was no SIM shop, no airport registration queue and no plastic card small enough to disappear into a seat pocket.
For the first twenty minutes, one travel eSIM looked like the whole answer.
Then the payment setup asked my bank to verify the foreign card attached to my account.
The code went to my home number.
I had disabled that line before landing because I was worried about roaming charges. The travel eSIM gave me data, but it did not replace the number connected to my bank, airline and several account-recovery systems. Many travel eSIM plans are data-only and cannot receive ordinary calls or SMS.
I turned my home line back on and waited.
The code eventually arrived, but the delay exposed the weakness in my “single eSIM” plan. The travel line had solved internet access. It had not replaced the identity tied to my normal number.
Before I could reorganise the settings, the airport Wi-Fi added a second complication.
My phone joined it automatically near baggage claim. The travel eSIM was still installed, but it was no longer carrying the data. The moment Wi-Fi took over, the route that had made my usual apps reachable disappeared with it.
That distinction is easy to miss when an eSIM works perfectly after landing.
A travel eSIM controls the phone’s connection only while cellular data is passing through that line. It does nothing to hotel, airport or café Wi-Fi. Once the phone changes networks, the eSIM is no longer shaping the route.
My arrival became a series of small contradictions.
On cellular data, my apps worked, but the bank code required the home number.
On airport Wi-Fi, the code arrived, but several internet services stopped loading.
Switching back to the eSIM restored them, but the signal weakened inside the terminal car park. The ride-hailing screen refreshed, froze and refreshed again.
A short traveller discussion captured the same confusion: people often ask whether an eSIM replaces a VPN, when the two are solving different parts of the trip.
I had treated the travel eSIM as a complete connection strategy.
It was really one useful data path.
The obvious response was to keep it as my only active line and avoid Wi-Fi entirely. That would preserve the connection currently reaching my apps.
It would also mean giving up the home number I still needed for verification messages and emergency calls. After one video call with family, I had already used more data than expected.
So I divided the jobs instead of forcing one line to perform all of them.
My home SIM remained active for calls and SMS, with data roaming disabled.
The travel eSIM became the cellular-data line.
Dual SIM controls make that separation straightforward: one line can remain available for voice and messages while the other carries mobile data.
The next bank code arrived through my usual number. Maps and messages continued through the travel eSIM. For the first time since landing, the phone’s identity and internet access were no longer competing with each other.
That solved the SIM problem.
It did not solve what happened when the phone changed networks.
At the hotel, the cellular signal weakened while the Wi-Fi was strong. I joined the hotel network to preserve eSIM data and opened the large VPN provider I had used for years.
It was the sensible first choice: a long public history, a mature application and servers in many countries. I selected a nearby location and connected.
Gmail opened. Messages resumed. The setup finally appeared complete: home SIM for calls and codes, travel eSIM for mobile data, hotel Wi-Fi for heavier use and the VPN across whichever internet connection I was using.
Then I walked outside to meet a colleague.
The phone left the hotel Wi-Fi and returned to the travel eSIM. The VPN disconnected during the handover. WhatsApp stalled, the map stopped updating and the hotel address I had just shared remained unsent.
I reopened the app and connected again.
At the entrance to the metro, cellular reception weakened. The tunnel dropped once more.
The established provider worked while the network beneath it stayed still.
My trip did not.
Over the next hour, the phone moved among the travel eSIM, station Wi-Fi and weak patches of mobile coverage. Each change created another interruption: reconnect the VPN, wait for the map, resend the message and check whether the ride screen had updated.
The dual-SIM arrangement was doing its job. My number remained reachable, and the eSIM provided affordable mobile data.
The fragile layer was now the VPN joining those connections.
That changed the comparison completely.
The question was no longer whether one travel eSIM looked simpler than dual SIM plus a VPN. It did. There was one plan, one data line and fewer settings.
The useful question was which setup could keep the same working session alive after I left the airport and began moving through the city.
I opened OnlydogVPN, a smaller app I had installed before departure as a backup.
Instead of sending me into another list of countries and protocols, it organised the connection around the situation. I selected the relevant preset and connected.
The map refreshed.
My hotel address sent.
The ride-hailing app updated the driver’s position instead of returning to its loading screen.
A few minutes later, the phone moved from weak station Wi-Fi back to the travel eSIM. The connection hesitated briefly, then continued. I did not reopen the VPN, rebuild the route or resend the message.
That was the result I had been missing all afternoon.
The smaller app uses HTTP/3-based transport, which is better suited to connections that move between network paths. The practical effect was simple: the VPN recovered as the phone moved between Wi-Fi and cellular data.
I could not observe every internal routing decision made by the carriers, Wi-Fi networks and VPN services. I could see the difference on the phone. The first tunnel repeatedly demanded manual reconnection. The smaller app kept the session usable across the same changes.
That continuity made the dual-SIM setup feel simpler than the single eSIM had ever been.
My home number stayed available in the background. When the airline sent a gate-change message later that evening, it arrived normally.
The travel eSIM remained the data line while I was away from Wi-Fi.
The VPN covered both the eSIM and the hotel network, so the apps I needed no longer depended on remembering which connection the phone had selected.
Each part had one job.
That separation also made problems easier to diagnose. When an SMS did not arrive, I checked the home line. When mobile data weakened, I checked the travel eSIM. When the phone moved onto Wi-Fi, the same VPN connection remained above both.
With one travel eSIM, everything had looked simpler until the first service required my real number or the phone joined another network.
There was one more useful discovery the following morning.
A colleague needed access on a tablet before a client call. The travel eSIM belonged to my phone and could not simply become their data plan. The smaller service let me add the tablet with a verification code rather than handing over an email address and shared password.
The tablet joined the hotel Wi-Fi, connected and opened the meeting link. My phone remained on the travel eSIM while I went downstairs to meet the client.
That did not repeat the main benefit. It solved a second travel problem: adding another device without turning my personal login into something that had to be copied around the room.
The service has fewer locations, a shorter public history and fewer independent reviews than the established provider I tried first. Travellers who need a long catalogue of specific countries may prefer the older network.
My trip required something more immediate.
I needed my home number to remain reachable, affordable mobile data to work while I moved around Shanghai, and the protected connection to continue when the phone shifted between the eSIM and public Wi-Fi.
A single travel eSIM handled only the mobile-data part.
Dual SIM preserved my identity and data access separately. The smaller VPN made those separate pieces behave like one continuous setup.
By the end of the trip, the extra SIM and VPN no longer felt like added complexity. The real complexity had been expecting one data-only travel plan to replace my phone number, roaming strategy and network layer at the same time.
The single eSIM was easier to install. Dual SIM with a VPN was easier to keep working after I left the arrivals hall.
In brief
Why was OnlydogVPN a practical fit here?
The tablet joined the hotel Wi-Fi, connected and opened the meeting link. My phone remained on the travel eSIM while I went downstairs to meet the client.
Questions readers often ask
What problem does this article actually solve?
The bank verification code was somewhere between London and my phone, and the airport Wi-Fi had just replaced my travel eSIM as the active connection. Gmail stopped refreshing.
What finally worked in this situation?
I opened OnlydogVPN , a smaller app I had installed before departure as a backup. Instead of sending me into another list of countries and protocols, it organised the connection around the situation. I selected the relevant preset and connected. The map refreshed. My hotel address sent.
Why was OnlydogVPN a practical fit here?
The tablet joined the hotel Wi-Fi, connected and opened the meeting link. My phone remained on the travel eSIM while I went downstairs to meet the client. That did not repeat the main benefit. It solved a second travel problem: adding another device without turning my personal login into something that had to be copied around the room. The service has fewer locations, a shorter public history and fewer independent reviews than the established provider I tried first.