Viettel eSIM APN & Data Settings – Fix Slow or No Data

Viettel eSIMs are delivered with the APN 'viettel.vn' pre-configured, but a handful of phone models require you to enter it manually. Before diving into APN settings, confirm the eSIM has been activated: scan the QR code you received by email, then go to Settings > Cellular (or Mobile Data) and ensure the Viettel plan is turned on. Without that step, no settings will help.

Data roaming must be enabled for the Viettel line — without it, the eSIM can't connect to the local network. On iPhone, check under Settings > Cellular > Cellular Data Options; on Android, it's usually under Settings > Connections > Mobile Networks. If you're running two SIMs, make sure the Viettel line is selected as the primary data line. Finally, restart your phone after first activation; the network profile sometimes only loads after a reboot.

On an iPhone, navigate to Settings > Cellular > Cellular Data Network. Under the 'Cellular Data' section, enter 'viettel.vn' as the APN. Leave both the Username and Password fields blank — Viettel does not require authentication. If you cannot see the 'Cellular Data Network' menu at all, your carrier settings may be stuck; go to Settings > General > Reset > Reset Network Settings. This clears old carrier profiles without deleting your other data.

After entering the APN, toggle Airplane Mode on and off, or simply restart the phone. The 4G (or LTE) icon should appear within a minute. If you still see 'No Service', double-check that the eSIM plan is turned on and that data roaming is active for that line.

On Android, the path is: Settings > Connections > Mobile Networks > Access Point Names. Tap the + icon to add a new APN. Enter the following: Name: Viettel, APN: viettel.vn, MCC: 452, MNC: 04, Authentication type: None. Leave all other fields blank or at their defaults, then tap Save and select this APN as active.

For Samsung Galaxy S20+ owners, there is an extra field called 'APN protocol' — set it to IPv4/IPv6. On Pixel 3 and newer, after saving the APN, restart the phone and check for a 4G or LTE icon in the status bar. If the icon shows 'E' or 'H+', the APN may not have saved correctly; repeat the steps and reboot again.

Data roaming is not optional for Viettel eSIM — it must be turned on for the eSIM to connect. On iPhone, go to Settings > Cellular > Cellular Data Options and enable Data Roaming. On Android, look for 'Data roaming' under the same Mobile Networks menu. Without it, the phone will treat the local network as roaming and refuse data even with a correct APN.

If you expect 5G but only see 4G, check that 'Voice & Data' is set to '5G Auto' (iPhone) or that the preferred network type includes NR/LTE (Android). Viettel's 5G coverage is concentrated in central Ho Chi Minh City, Hanoi, and Da Nang; in smaller cities you'll rely on 4G, which is fast enough for maps, social media, and video calls. After long periods of inactivity (e.g., overnight), the radio can idle; toggling Mobile Data off and on usually restores the connection.

If you've followed all steps and data still doesn't work, delete the eSIM profile entirely and re-scan the original QR code. Make sure you still have access to the QR code (a screenshot or printed copy helps). Also verify your phone supports Viettel eSIM: iPhone XS and newer (US, EU, and Korean models work; mainland China/Hong Kong/Macau iPhones do not have eSIM), Samsung Galaxy S20 and newer, Google Pixel 3 and newer.

Contact simvietnam support via email at support@simvietnam.telebox.vn if data remains down after 15 minutes of troubleshooting. If data works but is very slow, network congestion may be the culprit — in busy tourist areas during peak hours (6–9 PM), Viettel speeds can drop noticeably. Resetting network settings on both iOS and Android often clears stale carrier configurations and restores normal speeds.

Install the eSIM at least one hour before you leave for Vietnam so the profile has time to activate on the network. Keep a screenshot of the QR code in your phone's gallery or print a backup — if you lose access to the email, you won't be able to reinstall the profile. When traveling between regions, expect a brief 1–2 minute data drop while your phone re-registers on a new tower; this is normal.

If you're using dual SIM with your home SIM still active, some phones combine MMS/SMS settings from the home line. Make sure the MMS APN is also set to 'viettel.vn' for the Viettel line. Otherwise, you might experience odd behaviour like no picture messages or data stalling after an incoming SMS.