Never seen before in my life...

I have a rather strange and interesting problem. I am no stranger to computers, I’ve been dealing with them since 1984, and I’ve even taken an A+ certification course. Unfortunately I’m dropping further and further out of the loop as it were, as I get older. So here’s the problem I’m having. Every day I like to watch streaming video from a news site, during break at work. Until about 4 days ago, all was working just fine, but now I can no longer access the streaming video feed, and it seems to have something to do with the internet connection or modem. In a nutshell; the website is working properly as verified at home, and, by accessing the correct page via my IPhone at work, through the 3G network ONLY. The IP Company worked with me yesterday and said all is well with the internet, which is also verified by the fact that I can access streaming video from another news site, and also YouTube, and other sites as well with no issues at all. I have two computers and an IPhone in the office, and all of them will open up to the same “let’s say stock type” page of the news site, through the work network, which I can only see when logging on through the work network. If I turn Wi-Fi on for my IPhone, and access the page, that stock web page shows up. If I turn off Wi-Fi and use 3G to access the page, it comes up to the correct selection screen for the network. If I then turn on the Wi-Fi again, and refresh the page, the stock page comes back again. This page that comes up is similar to the actual page that is supposed to come up, but different because instead of the option to choose between two channels, it only displays one show available. It displays a show that is coming up (always the same show and it’s the wrong one of course) with the option to watch now, which when you press it, does nothing. Both the modem and computers have been reset numerous times with no change. The history has been cleared, but it has nothing to do with the computers as the IPhone has proven by accessing it through regular 3G. I accessed the modem to try to find out if the web page has been blocked, and it shows no pages blocked, but I’m not an expert in modem/routers by any means. I have never seen anything like this before, any ideas please?