Network performance issues

Hey guys,
I have been having problems with the performance with PoE for a few years now. But since it has been off and on it was somewhat manageable, only it turned up again and my game is basically unplayable.

For whatever reason the network bar (when pressing F1) shows insanely high spikes into the thousands and obviously my game just stops responding and stutters. I've had this issue as mentioned for quite some time now and I changed hardware parts over this time too which makes me think it's at least not that.

What i have tried: change of hardware, installing and reinstalling on an SSD, changing servers (my ping is usually around ~20 in Europe), changing directx to vulkan and vice versa, the tips with renderer etc that are mentioned in your guide.

What is weird to me is the off and on nature of this, since I often managed to play normally with the occasional, yet still very annoying, appearance of this issue. Only now it persisted for 2 days which is why I finally wrote you.

My specs:
RTX2070 Super (before i had a GTX970 with the same problem)
16GB DDR5 Ram,
AMD Ryzen 7 3800XT (before i had an INTEL 5 sth also same problem)
1TB Samsung SSD 970 EVO (before installed on and HDD same problem).

Renderer: Direct X12
VSync: off
Triple-Buffering: disabled
Antialiasing quality: off
Upscale Mode: NIS
Shadow qual: low
Sun shadow: high
Number of lights: medium
Water: high
Texture: high
Texture Filtering: 2x anisotropic

Forgive my technical ineptitude I'm not quite sure on how to add the screenshot but it basically shows a screen almost with almost no enemies in sight and the network bar at around 800. It can go a lot higher and it spikes -> goes down -> i can move for a few frames and goes back up again with the screen stuck.

Hope there is a solve for this.

Thanks in advance

Edit: I should mention that it does not seem to be an ISP issue since I have no problems at all playing different games online (Dota 2, CS2, Nightreign) + watching streams.