I'm using BM3.5 on NW4.11 server. I got a 502 bad gateway error
message recently. When browsing some web page require login or
searching page, it will show on the browser. But when I refresh the
page, the web page can see again.

Is it a DNS setting problem, because I set the DNS resolver list to
our internal DNS first. And then the internal DNS set forwarder to ISP


As the same time, when I set proxy parameter on my browser, the
problem disappear but using transparent proxy it happens again.

Please advise, thank!