iRule to disallow request Content-Length HTTP header from being sent by server

Hi,

I'm not sure but I think you must remove header on the response event, like this way:

when HTTP_RESPONSE {
    HTTP::header remove Content-Length
}

Unfortunately, I can't confirm if this is the best approach to solve the issue and remember to the notes from the article K42151600:

Impact of workaround: The impact of the suggested workarounds depends on the specific environment. F5 recommends testing any such changes during a maintenance window with consideration to the possible impact on your specific environment.

Note: The newly configured behavior is applied to new connections. Existing connections are not affected.

Regards.