How to determine issues pulling up internal device in browser.

OK, this is kind of a long shot, but I'm having an issue that hopefully someone can point me in the right direction on...
A little background...

We have a device which controls some fuel pumps/gauges - had been working fine until we had some network issues a week or so ago... or timing may have been a coincidence.   The device (which is accessible via a browser) is located in a remote building in which a local radio company has hooked up with wireless access via antennas so it works like any other device on our network with an ip address.  We had some issues with the antennas about 10 days ago and the vendor had to come out an fix.  We can ping the address once again, and it pings fine (not quite as quickly as something attached via fiber or copper but ok speed). I can attach to this device using IE on two computers....   but not on others.  I've gone through every IE setting I can see, I've reinstalled Java, flash player but still not working.  the vendor says it should work in chrome but can't get it to work in chrome on any of the computers.   How do I troubleshoot this further....i'm stumped as to why it works on one computer but not another that is right next to it.   Using same user to login on both computers.   From what I can see everything is identical.  Is there a way to use wireshark, I'm not real familiar with it but someone mentioned it.

On the computers that it won't come up on, the Brower never errors out, just sits and spins like it is trying to load.   Any ideas anyone?   thanks