Why two YI IoT camera, one video is smooth, the other is lagging? & Can I connect to a YI IoT camera without a WiFi password

Why two YI IoT camera, one video is smooth, the other is lagging?

1. Turn off other connected devices and try connecting separately.
2. Keeping YI IoT cameras close to the router.

Can I connect to a YI IoT camera without a WiFi password?

Supports connections without a WiFi password.

https://cameratechy.com/