DNS issue: Can not open certain websites at my laptop

I can not open websites from a specific server IP address at my laptop, connected to LAN wifi, similary, i can't open those website at my mobile phone if connected to same home Wifi. But when i connect same laptop with my mobile internet, i can open those websites.
I have flushed the DNS and have done all tricks available, but nothing worked. Please bid only if you are expert in this area.