we have an ASP.NET 4 website deployed on two nearly identical VirtualBox VMs with IIS 7.5. They are both hosted on the same Ubuntu system with Apache 2.2.14.
Apache decides by hostname (live.domain.com or staging.domain.com) to which VM the query is sent. It has two VirtualHosts with ProxyPass/ProxyPassReverse configured and selects the VM by it's IP (the VMs are connected by VirtualBox's "Host-only" virtual network adapter to the host).
This setting works fine, except that some requests do not finish. The browser tries to download the file (e.g. a static JS file) for exactly 5 minutes, when Apache returns a 502 Proxy Error result. Apache logs say that IIS didn't respond in time. In IIS logs the request doesn't even appear.
Any hints where to look for these occasional errors? Apache? VirtualBox virtual network adapter? IIS?
Excerpt of Apache VirtualHost config:
ServerName staging.domain.com ProxyRequests off ProxyPreserveHost On <Proxy *> allow from all </Proxy> ProxyPass / http://192.168.56.103/ ProxyPassReverse / http://192.168.56.103/