Network Security Key Mismatch

Question

I'm not sure if it's relevant but about a week ago I upgraded from copper fibre to full fibre. My Windows 10 machine was perfectly happy (i.e. I hadn't needed to change my router and it still connected ok) But I've Windows 7 machine here and when I try connecting that one, a dialog box pops up asking for my security code. I looked online and the consensus was that's it wants me to enter my router's password. But when I try that, it initially seems like it'll work but after 10 seconds or so, an identical box pops up saying Network Security Key Mismatch. I've checked that the password is correct (and correct upper case / lower case) but I still get this error. Is the Security Code window expecting something else?

Answer 1

The Network Security Key dialog is asking for the Wi‑Fi network’s password (the wireless security key), not a different “code.” A mismatch error means the key being entered does not match what the router is currently using for that wireless network.

Given the symptoms:

1. Confirm the exact Wi‑Fi password
   • On a working Windows 10 PC already connected to the same Wi‑Fi:
     1. Open Settings > Network & Internet > Status > Network and Sharing Center.
     2. Next to Connections, select the Wi‑Fi network name.
     3. In Wi‑Fi Status, select Wireless Properties.
     4. On the Security tab, select Show characters.
     5. Use the value shown in Network security key on the Windows 7 PC.
2. Check the wireless security type on the router
   • Many newer routers default to WPA2/WPA3 or WPA3‑only. Windows 7 cannot use WPA3.
   • Sign in to the router’s admin page and check the Wi‑Fi security mode. If it is set to WPA3 only, change it to a mode supported by both devices (for example, WPA2‑Personal or a mixed WPA2/WPA3 mode if available).
   • Save the changes, then reconnect both PCs using the same password.
3. Ensure the network is using a supported encryption
   • If the router is using very old standards like WEP or TKIP, Windows may warn that the network is not secure and these can cause connection issues. The recommended setting is WPA2 or WPA3 with a strong password.
4. Remove and re‑add the Wi‑Fi profile on Windows 7
   • On the Windows 7 machine, remove any saved profile for that SSID, then reconnect and enter the confirmed password from step 1.

If the password is confirmed from the working Windows 10 device and the router is set to a security mode supported by Windows 7 (e.g., WPA2‑Personal), the Network Security Key mismatch error should be resolved.

---

References:

• Connect to a Wi-Fi network in Windows
• Setting up a wireless network in Windows
• Wi-Fi network not secure in Windows