Not able to access a website when connected to my office network

Hi,

I want to access a particular website, but not able to do so, when connected to my office broad band network. But I am able to access the same web site, when I am connected to my phone network. And let me say that, speed is not at all an issue, as rest all the websites are opening quite easily. How can I access the same website, when I am connected to my office network. And also tell you that, there is no user access restriction on my office network, as I control that. I was able to open that site few days back but now not being able to do so.

I am not able to open the site on any of the browser, chrome, opera , edge and IE. My system is windows 10 based