eSIM not working in Vietnam
Your Drift Asia eSIM has no data in Vietnam? Here is the real fix, step by step, iPhone and Android, with Vietnam operator APN reference.
Networks in Vietnam
Vietnam has 3 major operators, all compatible with travel eSIMs:
| Operator | Coverage | Technology |
|---|---|---|
| Viettel | 1er réseau, meilleure couverture nationale y compris zones rurales | 4G/5G |
| Mobifone | 2e réseau, bon débit en ville | 4G/5G |
| Vinaphone | 3e réseau (groupe VNPT), couverture correcte | 4G/5G |
Your eSIM connects to one of these networks (most often Viettel). 4G coverage spans the large majority of tourist and urban areas.
Diagnosis in 5 steps (in this order)
Work through these before anything else. Nine times out of ten, the fix is in this list.
Steps 2 and 3 fix the large majority of cases. Data roaming is required for any travel eSIM. It does not add charges on a Drift Asia plan.
Airplane mode as a diagnostic tool
Toggling airplane mode forces the phone to detach from the network and search fresh. It is faster than a full restart and clears most handover issues (when the phone stays attached to a ghost signal after a long flight). If after the toggle you see the operator name on screen but still have no data, the issue is almost certainly roaming (step 2) or data line (step 3).
Signal bars vs. data
A common trap: you see signal bars but nothing loads. Bars mean the phone detects the network, not that it is authorized to exchange data. That is exactly what happens with roaming off: signal is there, but the network refuses your data packets. Turn roaming on and data resumes.
APN in Vietnam: do you need to set it?
No, in 99% of cases. Your travel eSIM sets its own APN automatically via the installed profile.
Do not enter your home operator's APN or a Viettel APN found online into the eSIM line. Those are APNs for local physical SIMs, not travel eSIMs. Entering one overwrites the profile's APN and breaks your data instead of fixing it.
For reference only (do NOT enter these on your eSIM line):
| Operator | Primary APN | Alt APN | Note |
|---|---|---|---|
| Viettel | v-internet | e-connect | 1er réseau, meilleure couverture nationale y compris zones rurales |
| Mobifone | m-wap | m-3g | 2e réseau, bon débit en ville |
| Vinaphone | 3m-world | m3-world | 3e réseau (groupe VNPT), couverture correcte |
Manual APN entry only if support asks with a specific value. Full procedure: Do I need to set an APN?
Country-specific notes for Vietnam
Ha Long Bay and northern islands
Coverage is good on the mainland (Ha Long city, Bai Chay) and Cat Ba island. In the open bay, on cruise boats, signal is intermittent. Do not expect continuous data during the cruise itself.
Sapa and northern mountains
Sapa town is well covered. Treks through the rice terraces (Ta Van, Lao Chai) have uneven coverage. Viettel covers these areas best. Force network selection to Viettel if you lose signal on a trek.
Reunification Express (Ha Noi to Ho Chi Minh)
The 30-36 hour journey crosses mountainous central sections (Hai Van Pass, tunnels). Drops of 10-20 minutes are normal in these sections. Station stops (Hue, Da Nang, Nha Trang) offer excellent connectivity.
Still not working?
Prepare these three things and contact support:
Support typically identifies the cause in a single exchange.
FAQ
Why does my eSIM have no signal in Vietnam?
Most likely data roaming is not turned on for the eSIM line. Enable it in your mobile data settings. If you see signal bars but no data, also check that the eSIM is set as your data line.
What APN should I use for my eSIM in Vietnam?
None. The eSIM sets its own APN automatically. Do not enter an APN for Viettel or any other local operator.
Do I need to enable roaming to use my eSIM in Vietnam?
Yes, it is required. Data roaming must be ON for the eSIM line. There is no extra charge. Roaming is already included in your plan.
My eSIM worked yesterday in Vietnam but not today. What do I do?
Check that your plan is not expired or used up. If it is still valid, toggle airplane mode (10 seconds on, then off). If that does not help, force network selection to Viettel then switch back to automatic.
Will my eSIM work on a Ha Long Bay cruise?
Intermittently. Signal comes from towers on nearby islands and is not guaranteed in open water. You will have good connectivity at departure and return (Ha Long city) and at some points during the cruise.