Question about Devolo Magic 2 LAN Starter Kit 1-1-2

For all those with connection problems: I had very fluctuating transfer rates. From 60 Mbit/s to 1.0 Mbit/s, the latter being the rule. I already have a replacement device and wanted to return the product because the promised feature was not even close to being met and switch to WLAN. However, there is a solution to my problem: in the Devolo Cockpit, go to the configuration page of the device, click on "Powerline" in the left-hand tabs and then switch to SISO in "Compatibility mode" (MIMO is the default). This must be done separately for each connected device. This has solved my problems to the extent that I have a stable transmission rate of 100 Mbps. Of course, this does not correspond to the advertised 2400 Mbit/s, but you cannot expect that in an old building. I was a bit surprised by Digitec's support, which consisted of exchanging / taking back the device, no support regarding a possible problem solution as described above.