TCP Keepalive Problems in Virtual Box - linux

Question

I ran into issues with TCP Keep Alives in Virtual Box maybe someone can help me out here.
Our software runs inside a Linux VM running with Virtual Box on Windows.
From there a TCP connection is established where we try to check broken connections by enabeling TCP Keep Alives.
Since we want to detect broken connections fast we changed the defaults of those on OS level (since thats where you're supposed do this) and thats where we keep running into issues with Virtual Box.
I did a little investigation with a simple python script and wireshark and got some strange results.
The python script looks like this:
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)
s.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
print(s.getsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE)) # seconds
print(s.getsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPINTVL)) # seconds
print(s.getsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPCNT))
s.connect(("10.33.42.0", 2112))
s.recv(16)
Pretty basic. I establish a tcp connection and block with the recv call. The other side never sends anything (I just use netcat) so that the keepalive would apply after the TCP_KEEPIDLE intervall.
Also I print out the keepalive settings to see if they were picked up correctly.
So now I ran this script in different environments and got pretty different results with it.
Running it on Plain Linux works. I can set the TCP_KEEPIDLE to 10 sec and wireshark shows that every 10 sec an TCP Keep Alive is sent.
Next I ran it inside WSL (Windows-Subsystem Linux) I use for development purposes and there the first thing came up that was strange:
The settings seemed to be picked up correctly (since the prints of script) resembeled the settings I did on OS level which had a TCP_KEEPIDLE of 10 sec, but when I looked into Wireshark i saw that a keepalive was sent every minute (no matter what I configured). I can't explain where this 10 sec intervall comes from (I assumed that it could be from the windows settings, but they were on default which would be a KEEPIDLE of 2 hours).
Then I ran it on our actual deployment (VM running Linux on Windows). The output of the scripted looked good again. Picked up the 10 sec of TCP_KEEPIDLE, but I never saw a single Keepalive message.
My first guess here again maybe the windows settings are used even though the script prints the Linux settings. The intervall would be 2 hours there by default, which would explain why I don't see any message in the 10 minutes I tested.
So I changed the settings on the Windows host which did not make a difference for the VM setup.
But what I did notice when running the python script directly on Windows it still printed the default settings even though when looking at Wireshark the keepalive worked as configured. So it seems that python does not always get the right settings when getting them with getsockopt.
I'm pretty much in a dead end here. Since I don't know what settings are applied in my two VM setups (WSL and Virtual Box).
Is there someone here that has a little more insight on what happens with Keepalive settings in VM Scenarios and where the settings come from there?