That airport products only wirelessly extend other airport products.
Apple has designed their "extend a wireless network" function as a proprietary feature to work with other Apple routers. I've tested maybe a dozen different third party wireless routers over the last few years, and I have yet to find one that is compatible with Apple's "extend" feature.
But, no one has tested every router or hotspot to see if there might be a device that is actually compatible with Apple's settings, so I suppose it is possible that a few devices might actually be able to do this.
That statEmmet is wrong though because I have my airport express 2nd gen wiressly extending my network from my pocket WiFi hotspot through sprint.
Have you checked to verify that the AirPort Express is really "extending" the hotspot network.....and not simply "joining" the network? The Express does not extend the wireless at all when it joins a network, and it can join virtually any network for use with AirPlay.
So, this often confuses users into thinking that the Express is extending a network.....when it isn't.
There are several ways to test to find out if the Express really is extending the hotspot wireless. Simplest would be to use a Mac, but an iPhone or iPad could work if AirPort Utility is installed on the device.
But, even in the remarkable event that the Express really can extend the hotspot wireless, that does not mean to imply that it will work with other 3rd party devices. You would have to check on a device by device basis. I've never found an Xfinity router that would be compatible with an Express to extend the network wirelessly.....but I haven't tested every Xfinity device. I doubt that anyone has.
What device do you have to run a few quick checks?
As far a web log in for an Express to extend a network, Apple provides no settings for this. You have to use AirPort Utility on a Mac, iPhone or iPad to configure the Express. Assuming that the Express might be compatible with a third party device to extend the network wirelessly, the only way that the Express can connect is to select the wireless network and provide the wireless password for the network.
Finally, if the Express can extend the network wirelessly, it will only take a few minutes to set it up. If the Express will not work correctly after a few tries......it likely never will.
