Why Is My eSIM Slow in Taiwan? Causes and Speed Fixes

A slow eSIM connection in Taiwan does not always mean that the eSIM is faulty. Mobile speed can change because of local signal conditions, network congestion, your phone settings, the selected network technology or the conditions of your data plan.

The first step is to identify whether the connection is consistently slow or only weak in a particular location. Speeds may temporarily fall inside railway tunnels, underground stations, crowded tourist areas, mountain regions and buildings with thick walls.

You should also check whether your plan still has high-speed data available. NoveSIM unlimited-style plans include 1GB of high-speed data during each 24-hour period. After this allowance is used, the connection may continue at a reduced speed until the next daily reset.

Quick answer: Move to an open area, confirm the Taiwan eSIM is selected for mobile data, keep Data Roaming enabled, use Automatic network selection, check the APN is data.esim, disable Low Data Mode and restart the connection with Airplane Mode for 30 seconds.

What Speed Should You Expect From a Taiwan eSIM?

A travel eSIM uses available partner networks in Taiwan. The actual speed is not fixed and can vary throughout the day and during your journey.

Performance depends on:

• The strength of the local mobile signal.
• The partner network available in your location.
• Network congestion.
• Your phone’s supported frequency bands.
• Whether the phone is connected to 4G, LTE or 5G.
• The type and conditions of your plan.
• Background activity on your phone.
• Hotspot use and connected devices.

Even when two people stand in the same place, they may receive different speeds because their phones support different network bands or connect to different cells.

Common Reasons Your Taiwan eSIM Is Slow

Possible Cause	Typical Sign	Recommended Action
Weak local signal	Few signal bars or frequent disconnections	Move outdoors or closer to a populated area
Network congestion	Slow service in crowded places or peak hours	Wait and test again later
High-speed allowance used	Connection was fast and suddenly became slower	Check plan usage and reset conditions
Incorrect network mode	Phone remains on 3G or another older standard	Select 4G, LTE or 5G automatic mode
Incorrect APN	Signal appears but data is unstable or unavailable	Use data.esim
Low Data Mode	Apps load slowly or restrict background activity	Disable the setting temporarily
Hotspot or background downloads	Data is consumed quickly and pages respond slowly	Pause updates, backups and tethering

1. Check Your Location and Signal Strength

Mobile coverage is usually strongest in cities and populated travel areas, but local conditions still affect performance.

Speeds may be weaker in:

• Underground metro stations.
• Railway and road tunnels.
• Airport basements.
• Mountain areas.
• Remote coastal routes.
• Elevators and underground parking.
• Buildings with reinforced concrete walls.

Move near a window or outdoors and test again. If the connection improves immediately, the problem is likely local coverage rather than the eSIM profile.

2. Check Whether the Network Is Congested

Mobile networks divide available capacity among connected users. Speed can fall when many people use the same cell at once.

Congestion is more likely:

• During morning and evening commuting hours.
• At major festivals and events.
• Inside busy shopping areas.
• At airports after large flight arrivals.
• Near popular night markets.
• At crowded tourist attractions.

If signal strength is good but performance is temporarily poor, wait and test again from another location or at a less busy time.

3. Check Whether Your High-Speed Data Has Been Used

If the eSIM worked normally and then became much slower, the plan may have reached a high-speed threshold or used its fixed-data allowance.

Unlimited-style NoveSIM plans

NoveSIM unlimited-style plans provide 1GB of high-speed data during each 24-hour period. After the daily allowance is consumed, speed may be reduced until the next 24-hour reset.

Reduced speed may still support:

• WhatsApp and other messaging.
• Basic navigation.
• Email without large attachments.
• Light web browsing.

Activities such as video streaming, video calls, large uploads and hotspot use may become difficult until the allowance resets.

Fixed-data plans

A fixed-data plan provides a defined amount of mobile data for its validity period. When the allowance is fully used, normal internet access may stop rather than simply becoming slower.

Check for high consumption from:

• Automatic photo backups.
• Operating-system updates.
• Application downloads.
• High-resolution video.
• Video calls.
• Personal Hotspot.
• Cloud file synchronisation.

4. Confirm the Taiwan eSIM Is Used for Mobile Data

Your phone may have switched back to your home SIM or another installed profile. This can create an unstable connection or make it appear that the travel eSIM is slow.

On iPhone

1. Open Settings.
2. Select Cellular or Mobile Service.
3. Tap Cellular Data.
4. Select the Taiwan or NoveSIM line.
5. Disable Allow Cellular Data Switching.

On Samsung

1. Open Settings.
2. Select Connections.
3. Open SIM Manager.
4. Select the Taiwan eSIM for mobile data.
5. Disable automatic data switching if available.

On Google Pixel

1. Open Settings.
2. Select Network & Internet.
3. Open SIMs.
4. Select the Taiwan eSIM as the preferred data SIM.
5. Disable automatic mobile data switching.

5. Keep Data Roaming Enabled

Travel eSIMs normally use partner networks, so Data Roaming must remain enabled on the travel profile.

If roaming is off, the connection may fail completely or repeatedly attempt to register, creating an unstable experience.

Use these settings:

SIM	Mobile Data	Data Roaming
Taiwan eSIM	Selected	Enabled
Home SIM	Not selected	Disabled

6. Check the Preferred Network Type

The phone should normally be allowed to use the fastest available compatible network technology.

Choose a mode such as:

• 5G Auto.
• 5G/LTE/3G automatic.
• LTE/4G automatic.
• Preferred network type: 5G or 4G.

Avoid locking the phone to 3G or an older network standard. Also avoid forcing 5G only, because the connection can become unstable when 5G coverage is weak.

Recommended approach

Use an automatic 5G/4G setting so the phone can move between available technologies.

7. Check the APN

An incorrect APN can cause slow, unstable or unavailable mobile data even when the phone shows a strong signal.

Use the following values when manual configuration is required:

Field	Value
Name	NoveSIM or Taiwan
APN	data.esim
Username	Leave empty
Password	Leave empty

After saving the APN, select it as the active profile on Android. Then turn Airplane Mode on for 30 seconds and reconnect.

8. Keep Network Selection on Automatic

Automatic selection allows the eSIM to register on an available supported partner network.

Manual selection can reduce performance if the selected network has weaker coverage in your current area or is not supported by the plan.

Use manual network selection only when customer support gives you a specific operator to test.

9. Turn Airplane Mode On for 30 Seconds

Airplane Mode forces the phone to disconnect from the current cell and complete a fresh network registration.

1. Turn on Airplane Mode.
2. Wait 30 seconds.
3. Turn Airplane Mode off.
4. Allow several minutes for reconnection.
5. Turn off WiFi and test again.

This simple step can improve performance after moving between cities, leaving a tunnel or changing mobile settings.

10. Restart the Phone

A restart can clear a temporary network process and apply changes to the APN, network mode or SIM preferences.

After restarting, confirm that:

• The Taiwan eSIM remains enabled.
• It is still selected for mobile data.
• Data Roaming remains enabled.
• Network Selection is Automatic.

11. Disable Low Data Mode or Data Saver

Low Data Mode on iPhone and Data Saver on Android can reduce background activity. These settings do not usually limit the raw network speed, but they can make applications feel slower or prevent content from updating normally.

On iPhone

Open:

Settings → Cellular → Taiwan eSIM → Data Mode

Temporarily select Standard or Allow More Data on 5G where available.

On Android

Open:

Settings → Network & Internet → Data Saver

Disable Data Saver temporarily or allow unrestricted data for essential travel applications.

12. Pause Background Downloads and Cloud Backups

A connection can feel slow when other applications are using the available bandwidth in the background.

Pause:

• Photo and video backups.
• Cloud drive synchronisation.
• Application updates.
• Podcast downloads.
• Offline map downloads.
• Automatic video uploads.

Use hotel WiFi for large transfers whenever possible.

13. Check Personal Hotspot Usage

Hotspot use divides the mobile connection between several devices. A laptop may also start downloading large updates or synchronising cloud files without an obvious warning.

If the connection becomes slow while tethering:

1. Disconnect all hotspot devices.
2. Turn Personal Hotspot off.
3. Test the internet directly on the phone.
4. Reconnect one device at a time.

If speed returns after disconnecting the hotspot, one of the connected devices was probably consuming significant bandwidth.

14. Disable a VPN Temporarily

A VPN can reduce speed because traffic is routed through an additional server. Performance may be especially poor if the selected VPN server is far from Taiwan or heavily loaded.

Temporarily disconnect the VPN and test the connection again. If speed improves, select a closer server or adjust the VPN protocol.

15. Close Bandwidth-Heavy Applications

Applications can continue using data even when they are not visible on the screen.

Common examples include:

• Video streaming services.
• Social media video feeds.
• Cloud storage applications.
• Navigation with live map downloads.
• Video conferencing tools.
• Automatic media uploads.

Close unnecessary applications and test again with a single browser page.

16. Check for a Phone Software Update

Outdated software can sometimes cause network registration or modem problems. Install important system updates before travelling when possible.

Use stable WiFi for the update because operating-system files can be large.

After updating:

• Restart the phone.
• Confirm the eSIM remains installed.
• Check mobile data and roaming settings again.

17. Consider the Phone’s Supported Frequency Bands

Not every phone supports every network frequency used in every destination. A device may connect successfully but receive weaker coverage or lower speeds when it lacks important local bands.

This is more likely with:

• Older smartphones.
• Regional phone versions.
• Devices purchased for a different market.
• Budget models with limited band support.

Check the exact model number rather than only the commercial device name.

Why Is My eSIM Slow in Taipei?

Taipei generally has extensive mobile coverage, but speed can still vary because of high user density.

Temporary slowdowns may occur in:

• Taipei Main Station.
• Popular night markets.
• Major shopping districts.
• Busy metro interchanges.
• Large events and exhibitions.
• Tourist areas during peak periods.

Move a short distance, exit an underground area or test again outside peak hours.

Why Is My eSIM Slow on Taiwan Trains?

Speed can change while a train moves between mobile cells. Temporary interruptions are also common in tunnels and mountain sections.

For better reliability:

• Download tickets and reservation details in advance.
• Save offline maps.
• Avoid large uploads during the journey.
• Wait until the train exits a tunnel before reconnecting.

A temporary slowdown on a moving train does not necessarily indicate an eSIM problem.

Why Is My eSIM Slow in Mountain or Coastal Areas?

Remote parts of Taiwan may have fewer nearby mobile towers, difficult terrain or limited indoor coverage.

This can affect travel around:

• Mountain roads.
• National parks.
• Remote hiking areas.
• Isolated east-coast routes.
• Small coastal settlements.

Download essential maps, addresses and transport information before entering remote areas.

Is 5G Always Faster Than 4G?

No. A weak or congested 5G connection can perform worse than a strong 4G or LTE connection.

Use an automatic network setting so the phone can choose between 5G and 4G. If the connection repeatedly changes and becomes unstable, testing LTE temporarily may improve consistency.

Do not permanently restrict the phone unless there is a clear performance benefit.

How to Test eSIM Speed Properly

Use a consistent test process:

1. Turn off WiFi.
2. Disconnect any VPN.
3. Disable Personal Hotspot.
4. Close background downloads.
5. Move to an open area.
6. Confirm the travel eSIM is selected for data.
7. Run more than one test.

A single result may not represent the normal connection, especially when the phone is moving or the local network is busy.

Slow Connection or No Connection?

Symptom	Likely Issue
Pages eventually load	Weak signal, congestion or reduced speed
Messaging works but video does not	Reduced speed or limited bandwidth
Signal bars but nothing loads	APN, roaming or mobile data selection
No Service	Network registration or coverage problem
Connection stops completely	Data exhausted, validity expired or incorrect settings

Can You Switch Networks to Improve Speed?

Keep network selection on Automatic first. The profile should choose an available supported network.

Manual selection may help only when:

• Automatic registration is unstable.
• More than one supported network is available.
• Customer support recommends a specific operator.

Do not repeatedly select random operators. A visible network may not be included in the eSIM plan.

Can You Buy More High-Speed Data?

NoveSIM plans cannot normally be topped up or extended using the same QR code. When you need another allowance, purchase and install a new eSIM.

A working internet connection is required for installation. Use reliable WiFi and complete the new setup before the current plan expires or becomes unusable.

Do not delete the existing profile until you are sure it is no longer needed.

Do Not Delete the eSIM Because It Is Slow

Deleting an eSIM does not improve network speed. It can create an additional problem because many installation QR codes are valid only once.

Before contacting support, check:

• The current location and signal.
• The plan’s remaining high-speed data.
• Mobile data selection.
• Data Roaming.
• Automatic network selection.
• The APN.
• Background data activity.

Keep the profile installed during troubleshooting.

Fast Troubleshooting Checklist

1. Move outdoors or near a window.
2. Turn off WiFi.
3. Confirm the Taiwan eSIM is selected for mobile data.
4. Enable Data Roaming on the travel eSIM.
5. Disable automatic data switching.
6. Use automatic 5G/4G network mode.
7. Keep Network Selection on Automatic.
8. Check that the APN is data.esim.
9. Disable VPN and Personal Hotspot.
10. Pause updates and cloud backups.
11. Turn Airplane Mode on for 30 seconds.
12. Restart the phone.
13. Test again in another location.

Information to Send Customer Support

If speed remains unusually poor in several locations, provide:

• Your order number.
• Your exact phone model.
• Your current city or area in Taiwan.
• The signal indicator shown by the phone.
• Whether the phone displays 4G, LTE or 5G.
• A screenshot of the SIM settings.
• A screenshot of the APN settings.
• Confirmation that Data Roaming is enabled.
• Whether the issue occurs with hotspot, VPN or both disabled.
• Whether the plan worked faster earlier.

Do not share the complete QR code or manual installation details publicly.

Related Articles

• eSIM Not Working in Taiwan
• How to Use an eSIM in Taiwan
• How to Activate a Taiwan eSIM
• Mobile Data in Taiwan
• Best Mobile Network in Taiwan for Tourists

FAQ

Why is my eSIM slow in Taiwan?

Common causes include weak signal, network congestion, exhausted high-speed data, background downloads, hotspot use, an incorrect network mode or an APN problem.

Why did my Taiwan eSIM suddenly become slow?

You may have reached a high-speed threshold, entered a congested area or started a background download. Check your plan usage and phone activity.

How much high-speed data does an unlimited-style NoveSIM plan include?

It includes 1GB of high-speed data during each 24-hour period. After that allowance is used, speed may be reduced until the next reset.

What APN should I use?

Use data.esim when manual APN configuration is required. Leave the username and password blank.

Should I select 5G only?

No. An automatic 5G and 4G mode is usually more stable because the phone can choose the strongest available technology.

Can a VPN make my eSIM slower?

Yes. A distant or congested VPN server can reduce speed. Disconnect the VPN temporarily to compare performance.

Does hotspot reduce eSIM speed?

Yes. Connected devices share the same mobile connection and may run large updates or cloud synchronisation in the background.

Should I delete and reinstall a slow eSIM?

No. Deleting the profile does not improve speed and the installation QR code may be single-use.

Final Recommendation

If your eSIM is slow in Taiwan, begin by testing it outdoors with WiFi, VPN and Personal Hotspot turned off. Confirm that the travel eSIM is selected for mobile data, Data Roaming is enabled and the APN is data.esim.

Use automatic network selection and an automatic 5G or 4G network mode. Pause background backups, updates and large downloads, then refresh the connection by enabling Airplane Mode for 30 seconds.

If an unlimited-style plan became slower after heavy use, you may have reached the 1GB high-speed allowance for the current 24-hour period. Keep the eSIM installed, test again after the reset and contact support if unusually poor performance continues across several different locations.