I got a new extender for my wifi, and it says it has full connection and bars, but when I try to connect any device to it such as an iPhone, it just says "loading" (or the swirly thing that Apple products have) infinitely. Help?

Are you still using the same connection preferences that were saved on the device prior to the change to the router? You may want to delete/unremember them, restart the device, and try to establish a fresh connection.

Ill try that