BusinessObjects Board

Proxy 502 Error with some reports/users

Hi Team,
I am encountering weird proxy 502 error when I refresh certain reports. Those reports are spinning continuously with out any error. But we could see this error browser development tools. I have engaged network team and enabled the traces. They said packets are moving across servers they don’t see any firewall blocks at network level. Most probably issue would be at reverse proxy server level. But how can we determine the issue. We tried to analyze the reverse proxy logs, but unable to find the issue.
Can you guys help me on trouble shooting process?