Asking your aunt to use the same SSID and password on her new router as she did on her old router is the best way for your Wi-Fi Extender. To get back to your wifi router network. The extender understands nothing other than that it can connect to a wireless network without any complications.
There is, though, one slight caveat that might muck up this operation. This pairing would not work if you have already set up an extender to connect to the 2.4 GHz network of your router and, for whatever reason, your aunt only uses 5 GHz on its router.
(Your aunt is more likely to use just 2.4GHz on her modem when you’ve previously programmed an extender to connect to the 5GHz network of the router.)
If your aunt has renamed the wifi network, you can also set up your wireless extender and make any changes you need to make to the connection feature again, to connect to another SSID, or toggle which wireless band your extender uses to connect to your router.
I suggest that you launch a web search for the model number of your extender and open the manufacturer’s guides so that you can type various items in your web browser and see the configuration. If you are using Linksys Extender Setup, the configurations can vary from model to model.
Take Factory Reset:
Factory-reset your extender if you’re a little confused with, or just don’t want to bother with, the key configuration of your extender screen.
Usually, by holding down the reset button, you can do this, assuming it has one, for 5-10 seconds until the lights on the extender start flickering differently. However, review the unit manually to make sure that you are running this procedure properly.
You should follow your provider’s original configuration instructions for your personal extender, as though you have Netgear EX6100 setup, etc. Which should make it simpler to connect to your aunt’s latest router. You’ve got the extender running correctly for the first time.
Make sure you update your extender and router to their new firmware versions. You should be able to verify what firmware your router and extender use on each device’s web-based configuration page. You should then search for the support section of the computer maker. To see if the new firmware that it provides is what your system is running. If not, please fix it!