Btw you can used DD-WRT sa kahit anong wlan router even yung mga lumang wlan router mo from previous ISP / service provider. Done this twice with old ISP provided router and 2 cisco wifi router.
tama ba bro yung luma mong pldt zte router gusto mo gawing extender? sa bago mong subscription?
I think what you need is a new firmware not update. Tried this with several old routers from different Service provider.
Flash the existing firmware with the new one using DD-WRT (opensource wlan...