Content-Length, Upgrade, Connection and other headers are hidden on POST

I’m using an M95 to send and retreive data. (Revision: M95FAR02A08)

I’ve been using them for 3 years, and all is good, except I don’t see how to quit listening for response.
Problem is, that I cannot simply wait for no data available, since it can be some time until data is ready, therefore I want to read until I’ve read content-length characters.
Now the core of the problem. When calling with the modem I do not get any Content-Length, even though I “hardcode” them on my server side.

When doing a post to my API, I’m missing various response headers that appear just fine when using Insomnia. I’ve entered body and headers exactly as they are sent by the modem into Insomnia
I cannot for the life of me figure out why. any suggestions?
I get a fine reply, but I’m missing some of the headers that are returned from Insomnia
Insomnia request and response

M95 request and response:

Thanks in advance

Are you saying that there is no length indication in the post data returned by the server? I am not very clear about this, our module directly spit out the data returned by the server, and will not do any special processing, you can look at the configuration of the server, is it not going to return the length information