Try the following:

1. Move closer to a WLAN access point to get a better WLAN signal.

2. If possible, try to create a connection with some other device that supports WLAN (to see that the access point is really working).

3. If you keep getting an Incorrect password error, log in to your wireless router, and change the operating mode 802.11b/g/n to 802.11g only, and then restart/reset the router, and try to create a connection again. 

4. If a manufacturer-specific network mode (Turbo/Nitro/Super/Afterburner/108/SRX) is used, disable it and try the basic modes.

5. Check that DHCP (dynamic host configuration protocol) is activated in the wireless router.

6. Set the router to SSID visible mode (at least temporarily) to check that the phone finds your WLAN access point properly, and to prevent SSID typing mistakes.

7. In the router settings, remove the WLAN security temporarily, and try to create a WLAN connection from the phone without any security settings first. WPA2 (AES) is currently the strongest form of security offered by WiFi products, and is recommended for all uses; choose WPA2 with AES (do not use TKIP).

  • If you have older WiFi devices on your network that do not support WPA2 Personal (AES), select WPA/WPA2 Mixed Mode. This mode will allow newer devices to use the stronger WPA2 AES encryption, while still allowing older devices to connect with older WPA TKIP encryption.
  • If your router does not support WPA/WPA2 Mixed Mode, then WEP128 with Shared Authentication should be used (with a single WEP key in key index 1).

8. Check that you do not have MAC (Media Access Control) address filtering on in the wireless router settings. If your WLAN network uses MAC address filtering for security, you will need to know the MAC address for your phone, and then add it to the access list for that network before you can connect. To find the MAC address for your phone, do the following:

  1. Press Start, then swipe left to the App list.
  2. Select Settings > About > More Info.
  3. Then note the MAC address.

9. If there are many WLAN access points nearby, try to use a different wireless channel in your router. Select channel 1, 6, or 11 to optimize wireless performance.

10. Check if there is a software update available for your wireless router.

11. If you are using a public WLAN access point, it is possible that all IP addresses are in use. Try to create a connection again later.

12. On your Lumia phone, delete the non-functioning WLAN access point (internet connection) and connect it again:

  1. Disconnect the WLAN connection if connected.
  2. Press Start, then swipe left to the App list.
  3. Select Settings > WiFi.
  4. Press Advanced at the bottom of the screen.
  5. Tap and hold on the access point name and select Delete.
  6. Now add the access point again.
  7. On the Advanced screen, tap Add, type the network name in the Network name box, and then tap Add.
  8. On the Sign in screen, type the password in the Password box, and then tap Done.
  9. Tap the Back key once finished.