I've stumbled onto an issue I can't figure out and thought I best throw it at a great forum like this for help. I have to be missing some minor tweak.

MacBook Pro running 10.6.8
Firefox 11.0
Safari 5.1.2

Internet and computer function at normal speed on all but two file upload websites when using home LAN. When uploading photos on two different websites, one takes about 5 minutes to open the JAVA page. The other starts the upload but makes no progress. Same problem on both browsers.

If I connect to my AttMiFi internet connection the issue goes away using both browsers. If I connect to the home lan with a PC, the issue does not happen. Both connections check out within specifications nearly identical on the att.com/speedtest site.

I've restarted the Modem and Router, and MacBook pro. I've cleared cookies and internet history on the Firefox Browser, then uninstalled and re-installed the Firefox browser, but it is still happening.

Any clue on how to continue my troubleshooting further?