My Home Hub is also in the basement and is connected to the network via a switch. I've connected one camera near the Home Hub to its own Wi-Fi network because the regular Wi-Fi signal isn't strong enough. The other cameras are connected to the regular Wi-Fi network.

All the cameras store their data on the Home Hub. From what I've read in Reolink's manuals and tutorials, the problem is that cameras connected via the regular Wi-Fi network always need an internet connection. This means that if the internet goes down, those cameras won't be able to store data on the Home Hub.

However, the camera connected directly to the Home Hub can continue to store data without an internet connection.

(https://reolink.com/blog...)

The cameras can be integrated into the "normal" Wi-Fi and then added to the hub. They do not necessarily have to be on the WLAN that the hub itself can "send".
However, both devices must be in the same WLAN. It is therefore not possible to run the cameras in a guest WLAN (for security reasons, for example) and then run the hub in the WLAN that is used "normally".
This is also relevant: Not all cameras have already received the update for the hub. There are several still outstanding.

They just have to be in the same network, I even have a different wifi via Unify. Ps note compatibility list of cameras not all work :)