I also get the 504 error when tring to access some websites like tom.com,
sina.com.cn, etc. (but not all, most websites can be accessed normally).

I have NW5 sp6a BM35 sp3 . ADSL with one public IP. We are using Craig's
proxycfg file.

I added a www-http-st exception in the filtcfg for my laptop and disable
proxy in my IE, I still experience the 504 errors.
When I unload the filters, I still experience the 504 errors.

I can access those sites fine while connected the ADSL to my laptop

Thanks for any help,