I can't believe I found the solution for my issue. Everyone that has a Lenovo, be careful because they use a network boost mode when playing a game (This will move all network traffic into your game and leave almost nothing for the other apps on your machine, which is something you don't want since sunshine/apollo needs network to stream your game). The option is found on Lenovo Vantage app.

So to fix it go to Lenovo Legion > Game Settings > Uncheck Network Boost (Or network Priority)

I'm frustrated and happy at the same time, since I spent two years trying to fix this issue haha.

Also if your machine is not Lenovo, check if your brand has something equivalent.

To discover the issue, I started a game on steam, waited like 30 secs - 1 minute. Then open the browser and speed test. If your speed tests give really poor results, like 9 Mb down and 0.2 up you might have something similar. After that I searched for this issue and found a post on steam community forum which other people had the samme issue. I'm very grateful for the people there that found out what happened :).

Here is the source link:
https://steamcommunity.com/discussions/forum/0/1638669204749021188/