The ArcGIS Server output directory needs to be configured to go through the proxy server. Again a test file is placed in the output folder of the output directory and access is attempted through the proxy server via web browser, for example:
If the testfile is not seen then reconfigure the arcgisoutput proxy rule. The arcgiscache and arcgisjobs might also need a proxy rule depending on the services being used.
If this is successful check that the map services are pointing to the reverse proxy output directory in the service properties.
The ArcGIS Server service needs to be accessible via the proxy server. To test, use this in a browser :
and some xml should be returned. If the XML is not returned then reconfigure the ArcGIS/services proxy rule.