Just thought of sharing this tip if anyone else is having a rough time with sleep mode issues.
You probably have wake on network traffic turned on in the bios/power management settings.
So it was this problem, and I finally found a solution to it
I decided to browse some random hive threads not a while ago, and I came across a thread where was some advices about device manager. I decided to browse this tool by myself too, and I found a solution for my issues with sleep mode. Basically the issue was that my PC never stayed on sleep mode, it always turned itself back on after a while/instantly. I've tested this method and I'm using this myself too, so it's not dangerous.
First you open up your device manager, you do this by searching for it in your start menu.
Then you go to section "Network adapters", and expand it.
Now you should see your network driver's name there, right click on it, and hit "Properties".
Then go to power management, and uncheck the box that says "Allow this device to wake the computer".
Hit OK and try to go to sleep mode, the computer should no longer wake up by itself.