New laptop: no upstream via WLAN - only over LAN?

I bought a new laptop at MediaMarkt preinstalled (!).

No matter what network, I have no upstream, ie. At the Speedtest 0. Nevertheless, sporadically sometimes e-mails go out, sometimes not.

Over LAN everything works fine, 20000 upstream - no problems uploading.

Why is that? Firewall? 'Windows misconfigured? Possibly. Verbanuter WLAN adapter broken?

Incidentally, there are no problems in Downstream and Ping.

I would look for new drivers for the W-Lan adapter or reinstall the drivers.

You could exclude a software issue by using a USB stick attached to a live Linux system for diagnostics. The system boots from such a stick, the existing Windows installation is not touched (unless you start the installer). For example, you could do a speed test from the live system.

Go to the media market. Is the part new… They will help you.