To make WiiM Mini compatible with Netgear Nighthawk mesh network, please assign different names for your 2.4 Ghz and 5 Ghz. Then you can connect WiiM Mini to the 5 GHz network. When you're using it, please connect your mobile device to this 5 Ghz wireless network too. 

Here are the detailed steps:

1. Launch a web browser from a computer or mobile device that is connected to your mesh network.
2. Enter
3. Enter the router admin user name and password.
4. Select Customize WiFi Network.
5. Select the Customize 2.4 GHz WiFi Network or Customize 5 GHz WiFi Network check box.
You can add a WiFi network in the 2.4 GHz band and the 5 GHz band.
6. To control the SSID broadcast, select or clear the Enable SSID Broadcast check box.
7. To add an SSID, type a name in the Customized 2.4 GHz WiFi Network Name (SSID) or Customized 5 GHz WiFi Network Name (SSID) field. The default SSIDs are NETGEAR_2G and NETGEAR_5G. 
8. Set the WiFi security
9. Set a WiFi password in the Password (Network Key) field.
10. Click the Apply button.
Your settings are saved.