Default Blocked access to Playstore/secure sites on Android devices


I cannot access the Google Play Store and several secure sites on ANY android device (S3 i9305 & S4 i9505) via Wifi on my router.

Sites/store are accessible via data/simcard network.

An example is Hotmail. I can access it via my iPhone, and laptops. But Android devices cannot access Hotmail (can get to 'login' page, but after enter details page will not load).

I'm using a Dlink-DIR-632A (running DD-WRT v24-sp2).

What could be the cause?
Samsung Galaxy SIII 4G (i9305) international (EU) Resurrection Remix® 4.4.2 KitKat v5.0.9