ArcherC7 v5 2.4 WLAN very slow (1-2Mbits)

Hello. I have had the problem with my Archer C7 for months that the 2.4 WLAN is extremely slow. The WLAN only manages 1-2 Mbits maximum. I've tried all the settings, really everything, but these 1-2 Mbits remain.

The firmware is up to date.

I still have a DIR825, these problems do not exist here and the 2.4 WLAN on the old DIR825 is worlds faster.

Does somebody has any idea?
Or maybe there is someone who has the same model and can post his settings.

Many thanks in advance.

Searxh forum for archer c7 non ct drivers.