There may be confusion over how WiFi systems "work".
For a long time, WiFi routers such as the RAX54 were stand-alone units. They created a WiFi service area as large as the FCC limits on radio transmission would allow. The only way to cover more area was to add additional WiFi access points. These additional units could be connected to the router using Ethernet cable or over WiFi. Each unit created a new WiFi coverage area. The WiFi credentials for these additional units can be anything.
- They can be exactly the same as the primary router credentials, or
- They can be different.
When each WiFi device powers up, it scans the radio space for WiFi systems that are available and presents a list of them to the user to choose from. Sometimes, the device has already stored the password to some systems and has been set to "connect automatically" whenever it discovers one of these systems. This is what happens, for example, when a person comes home. The smartphone says, "Hey. I've been told to connect automatically to this system." and does it.
The problem with this method of expanding WiFi coverage is that each access point is unique. (no matter what credentials it is using) WiFi devices will not roam seamlessly between access points. Devices that are fixed in place (cameras, speakers, televisions, ovens, garage door openers, etc. etc. are not bothered by this. They never "roam". Mobile devices, however, can be annoying. As they get farther away from the original access point, their connection gets weaker (and weaker). Performance gets worse (and worse) Eventually, performance gets so bad that either the device drops the connection and begins to look for another, or the user gets fed up and tells the device to disconnect. Once disconnected, the device will look around and say, "here's a WiFi system that I know the credentials to. I'll connect to it."
I call this the, "Honey. The WiFi is so slow" problem. "You went upstairs (or came downstairs) dear. Did you remember to turn WiFi off and back on again?" Grrrrrrr.
Mesh systems solve this problem by communicating within the mesh and nudging devices to switch to another access point. Once connected to a mesh system, user devices can roam seamlessly from one access point to another.
This all has nothing to do with the WiFi credentials.
There is one situation where having a WiFi extender with different credentials solves a specific problem. Suppose that some device keeps switching from one access point to another. If a WiFi extender is set up with different credentials, then the device will have only one place to connect.
So, my concern is that by trying to save money by using an old technology, you may be sleeping on the couch.
