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Support for Enabling HTTP Keep-Alive?



I often need to access a PRTG Web Application that's hosted extremely far from my location. Accessing this server is extremely slow, and I recently realized that it's because by default, PRTG seems to have the Connection HTTP header set to "close". This means anywhere from 50% - 90% of my request time is spent setting up a new connection, doing another SSL handshake, etc., rather than reusing an existing connection.

However, I also discovered this knowledge base post which, despite the deprecated warning, actually works and allowed me to toggle the keep-alive header back on in PRTG version (the only difference being the registry flag is now called


So is this no longer deprecated? If the issue noted in the previous KB post was that idle connections were eating threads and memory, I imagine in the 7 years since its last update, it's been resolved (e.g. via a max time on persistent connections)? But if so, shouldn't this already be on by default? Or by turning it on, am I guaranteeing myself memory leaks and periodic server restarts?

If it's still not recommended to turn this on for those reasons, I just want to emphasize that most other sites solved Keep-Alive connections with HTTP/1.1 years ago, and at this point, many have also upgraded to HTTP2. Forcing a short-lived connection is effectively downgrading us to HTTP 1.0, and it's kind of painful.

connection-header core-performance http-header http1-1 keep-alive

Created on May 16, 2022 6:17:27 PM

Last change on May 17, 2022 6:42:26 AM by  Felix Wiesneth [Paessler Support]

3 Replies




This would be best handled by submitting a feature request. Although it is listed as deprecated, this means we just stopped active development to support this. Apparently, we didn't make any changes to prevent it either. To submit a feature request, please follow this link,

PRTG Feature Requests


Benjamin Day
[Paessler Support]

Created on May 17, 2022 6:53:50 AM by  Benjamin Day [Paessler Support] (1,441) 2 1



Hi Benjamin,

I'll make a feature-request for this, but until this is implemented as the default, I'd like to turn this on on my own. However, I'd like to know, is turning this on via that aforementioned registry edit not advised? And if not, what consequences could I expect from doing so?

Created on May 17, 2022 1:29:15 PM




No, the only issue you may encounter in the future is the removal of this key all together. For now, if it still works, this just means we haven't done anything with it since it was created.

Benajmin Day
[Paessler Support]

Created on May 18, 2022 11:28:57 AM by  Benjamin Day [Paessler Support] (1,441) 2 1

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.