There are a lot of reasons why your device may show a “No internet connection” error despite being connected to Wi-Fi. Best to check if this happens to other devices too, otherwise, check this article if all devices are unable to access the internet. Mobile Phone (iPhone/Android) Computer (Laptop/Desktop) WiFi isn’t working (using the Netcomm Modem) How to Change your WiFi name and Password (using the Netcomm Modem) How to Fix WiFi Speed Issue If you can’t access the Internet on your mobile phone, either through an app or a website, try these basic troubleshooting steps. Check if Wi-Fi is turned on and you’re connected to the right network (Wi-Fi) name Restart your wireless router Test the service. If it persists, proceed to the following steps 1. Try doing "Forget Wi-Fi" and reconnect. 3. Reset network settings (Note: When we reset the network settings, then all the stored wireless network passwords on the phone will be lost.) Android iPhone Restart the phone and check if the internet is now working. If the issue persists, try another device, otherwise, you need to contact the manufacturer or visit a repair shop. Back to Top 1. Laptop works somewhere else fine – Flush DNS (So the laptop is working fine at home or school (or any other location), but not here. We can then safely assume that it’s not an issue with drivers. The most common problem is a problem with the DNS.) d. Select Properties Click OK and close the other windows. d. Check the Ethernet connection again. If the problem is still occurring then proceed to step 11 8. Do a network reset. (“Network Reset” disables and then reinstalls network adapter and set other networking components back to their original settings. Windows will forget your Ethernet network, Wi-Fi networks, VPN connections, etc. This is why resetting the network should be the last resort.) 10. A new window will open warning you about what will happen when your network is reset. Click the “Reset now” button to continue and restart your PC. Note: DON’T manually reboot the computer as it will interrupt the process. It will take roughly 5 minutes for it to start rebooting. A popup message will show when there is only 1 minute left and then it will proceed to reboot. Back to TopYou might also want to check:
a. Open the Wireless networks on your phone
b. Tap on the Wi-Fi network name
c. Tap forget and confirm it
d. Reconnect to the Wireless network by tapping on the name in the Wi-Fi list and entering your WiFi password.
2. Restart the phone and check the internet is working over WiFi. If the internet is still not working, proceed to the next step.
1. Open Settings
2. Scroll down to System and open it
3. Tap Advanced
4. Tap either Reset or Reset Options
5. Tap Reset Wifi, mobile, and Bluetooth or Reset network settings
6. Confirm it and your device will restart.
1. Open Settings
2. Tap General > Reset
3. Tap Reset Network Settings
Start with the following steps:
a. Press Windows key + R ( a Run dialogue box will appear)
b. Type the following command ipconfig /flushdns and press enter
c. Check your internet access again
2. If the internet is still not working, try setting a fixed DNS server.
a. Right-click on Start and select Network Connections
b. Select Change Adapter Options
c. Open your Network Adapter by double-clicking on the Wi-Fi Adapter
e. Select Internet Protocol version 4 (TCP/IPv4) and then Properties
f. Check the box “Use the following DNS-Server“
g. Enter for preferred DNS-Server: 203.29.125.2 and for alternate DNS-Server 203.29.125.66. 
Check your internet connection again.
3. Make sure Obtain an IP address automatically is selected under network adapter properties.
4. Restart the Laptop or Desktop and check the internet again
5. Still, if the internet is not working Disable or remove anti-virus/security software (Some security software can be the problem of internet connection errors. They block outgoing network traffic due to a fault or configuration error.)
a. Go to Start and launch Windows Firewall.
b. On the left side panel, select Turn Windows Firewall on and off.
c. Check the two options that allow you to disable the firewall.
6. Restart the Laptop or Desktop and check the internet again
7. Update the network card driver of the computer (need an internet connection for updating the driver. If possible, connect the computer with a mobile hotspot using WiFi. If the customer cannot connect the computer to a mobile hotspot proceed to step 12)
a. Press Windows key + X
b. Select Device Manager
c. Expand Network adapters
d. Find your Wireless network adapter
e. Right-click and select Update Driver software
f. Select Search automatically for updated driver software
g. Windows will search for a newer driver and install it.
9. To do that on Windows, type Network Reset in the Start Menu search.
11. After the reboot completes (it will take around 1-2 mins) check the internet status.
See Also
Learn how to Connect a Router to a Modem | T-Mobile 5G Home InternetSolved: No Internet Connection Windows 10Internet Connection Types Explained - CNETBoost Your Internet for Free: My Secrets to High-Speed at Home