Can't surf while downloading?

Ca
2

I screwed my new PC together today. In this I have installed a Gigabyte X570 Aorus Elite. Here my PC is connected to the network via D-Lan.
I have no chance to surf the Internet when I start downloads. It doesn't matter whether it's Steam, Epic or anything else.
With my notebook (connected via Wi-Fi), everything works without problems. Download + surf no problem and runs at the same download speed as the PC.
Do you have a tip here? Is it probably on the D-Lan? (Currently no chance to test via direct LAN connection)
Is it on the mainboard?

It is strange that the WLAN has no problem, but now I have extreme problems with my PC.

(PS: I have already deactivated IPV6. No success)

Sa

Probably driver problem

Ca

It actually had to do with the D-Lan adapter. I was still able to make a direct connection from the PC to the modem. Everything went smoothly. Even firmware updates for the D-Lan didn't work. So it was generally just the adapters. PC is now connected directly to the modem and it runs great.