The server is using an Anti Xray plugin which can alter block information sent to your device from the server. They decide what the world map you get looks like. Server devs add ores everywhere and you can't see further than a few blocks under the ground. There is no way around this other than to hack their server and delete the anti-xray plugins. You could always try to get the world seed if it's not a custom world and then work your way from there. But in all honesty, stop xraying on servers that don't allow it.