@inlkcs 

so there are two ways.  You can copy the SSID of the host router or give the bands each a unique name. The Difference is this:

Same SSID makes it easy to switch between the Host and the extender automatically.  However some clients may not know which to connect to, especially if they are between the two.  So in these cases they will either constantly hop between the two or not connect at all.  The result is the same poor or no internet on these clients. 

Unqiue SSID removes this conflict but you have to manually switch between host and extender as needed.  

The other option you have if you have one of our compatible OneMesh routers and extenders you could use the OneMesh which converts the Extender into a remote Mesh Node and remove the conflict issue of having the same SSID.  OneMesh devices are here:  

@Carl thanks for the prompt reply. I'd like to get your advice on this question to make a final decision.

For most smartphones and laptops which are about to lose the signal of host router but already paired with the extender, which option would allow a faster switch from router to extender?

Let's say my smarthpone was already paired with the extender with different SSID before. I'm connected to host router, walking away from the source and about the lose the signal. Does it swtich the connection to the extender faster as the SSIDs are different?