9 months ago. Updated
You have set a proxy
Android tries to connect to google.com at boot.
If this connection fails, Android considers that there is no Internet connectivity.
To fix this issue, unset the proxy and reboot the device.
Also, unset the proxy before stopping the device to avoid this problem in the future.
For more information about Genymotin and proxies, refer to How to connect a virtual device to a proxy?
You are using quick boot (Genymotion Desktop - QEMU only)
This bug can occur after a quick boot. Launch the device with a cold boot instead. For more information, refer to Genymotion Desktop on-line documentation.
You are in China
If the device is started in China, WiFi will probably be disabled.
Genymotion devices try to connect to google.com at boot to verify the Internet connection.
Due to restrictions in China, this test fails.
The device then thinks that Internet is not connected.
Genymotion Desktop
To solve this problem, use a VPN on the host computer and connect to a non-Chinese network. Alternatively, use the following method.
1. Open a terminal and run the following ADB commands:
adb shell settings put global captive_portal_http_url https://www.google.cn/generate_204
adb shell settings put global captive_portal_https_url https://www.google.cn/generate_204
adb shell settings put global ntp_server 1.hk.pool.ntp.org
WiFi should then be available.
Genymotion Device Image
This problem occurs if Alibaba Cloud is used in the Chinese Zone.
For detailed instructions, refer to this article: I am using Genymotion Device Image on Alibaba, in the Chinese zone, and Wifi/Internet is not connected.