Wifi Extender not allowing me to visit certain apps/ websites for only my apple devices.

I recently bought a Wifi extender (from NetGear), to extend my ATT wifi. The wifi extender allows me to go to certain websites and apps, but not others. When going to ESPN.com, for example, it states that the server cannot be found. I do not have this problem with my family's non-Apple devices (PC and Android), but it is a problem on every iPhone/ MacBook in my household. I have already tried re-setting the router/ extender, updating my devices, and re-setting my phone. Does anyone know a solution?