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When you have an IIS working as a reverse proxy. the default configuration values cloud support small to medium loads. However, In the enterprise environment, these values need to be tuned up to suit the new high loads and the back-end server configurations. This article addresses error “This site can’t be reached” reported by IIS ERR_CONNECTION_RESET.

IIS reverse proxy ERR_CONNECTION_RESET error message

Confusing issue! 

Today’s adventure, We have an ADF application installed on Weblogic. That application is running behind an IIS reverse proxy. Though the application is working normally and its pages are loading normally, there are certain pages that fail to open showing error ERR_CONNECTION_RESET.

The developers are saying “It’s working on my PC”


As a good administrator, I will investigate using the deduction process. hence, what I will do.   

Initially, I will open the application directly using the URL of Web-logic deployment URL, that means, I opted out reverse proxy. Surprisingly, application pages including those pages work normally. That means the application has some requirements and ISS can’t fulfill them. Causing, connection to reset.

What causes it?

the ERR_CONNECTION_RESET errors appear in the browser console. This message sent by the reverse proxy indicating a failure in page caching or loading pages. It seems that these pages contain objects which can’t be split into default size of the proxy cache.


To solve that error, We need to increase the Response buffer cache and Response buffer threshold in IIS Server. By following steps

Firstly, Open IIS Administration console. Then, Click on the root structure on the left panel to view IIS icons. Secondly, click on the Application Request Routing icon.

IIS reverse proxy ERR_CONNECTION_RESET IIS main page

After that, Click Cache Configuration settings located on the upper right side. 

In the Cache configuration setting window navigate into the buffer settings section, then, Increase the value of the Response buffer cache and Response buffer threshold

Conclusion, IIS ARR buffer cache causes the ERR_CONNECTION_RESET due to insufficient buffer cache size. Therefore, Increasing the values will solve the issue.