Two wifi Ext names?

[PilotJaz]

Hi
I have set up and registered my extender but when I go to connect it there are two options. One with my wifi name and 2GExt and one with 5GExt. Which one do I use. I don’t think 5G is in my area yet.
And how do I change the name of the Ext once I work out which one to use ?
Many thanks

[plemans]

dual band routers/extenders have 2.4ghz and 5ghz signal.

It isn't 5G like a cellular technology. its different. 

5ghz is going to be faster than the 2.4ghz but it won't broadcast as far or through as much materials.