It is somewhat ironic that changing to a Dect phone system that will also allow VOIP calls has almost killed my internet connection. It seems to be caused by the SMPS supplied with the Siemens connection box rather than the phone itself. Unfortunately the DC input plug is the one size I don’t have so I can’t try a substitute. It even managed to get my Thompson ADSL2+ modem/router to continually reboot yesterday afternoon. I’ve tried mains filters everywhere and even ferrite rings but nothing will bring my internet back up to speed except unplugging the Siemens PS and rebooting the modem.