Hello, I have experienced problems with instability of network via Ethernet and WiFi with my DecoXE75

Speeds can vary from 15 Mb to 87 Mb ( maximum for me) on the same day and different AP's

So I decided to downgrade the firmware, went to th Belgian site and downloaded the 20241015 firmware, tried to install, but the tool says the file is not the correct one. I am a bit stuck here.

Can anyone suggest what to do ?

Thanks