Where is TCP processed - CPU? Networkinterface? Elsewhere?

[nero355]

The devices with Coreboot are "in production", so not easy to swap the OS.

I am not talking about swapping anything : Just boot a Live ISO from a USB Stick !!

And as the problem is with TW updates, not with the browser (see above): how to test then?

Download stuff manually via the browser or wget on the Terminal ?

So largely: Self-inflicted pain, one might say. It bugs me not to know, what is going on here.

I can relate to that! :)

OPNsense has no traffic shaper enabled, what should IPS/IDS do to the bandwith of one client, but not to another on the same switch?

It would be based on IP address but if you know for sure you have not configured anything in OPNsense or on the Client/Server that is having these issues then there is not much to do there I guess...