When I first got the QBox, I noticed some interference with another device (Homeplug). I wrapped the mains lead through a ferrite core and this helped enough to restore operation. However, I recently had to replace my ADSL modem/router and the new one seems more susceptible to mains-borne noise (the old one had an AC adaptor with internal rectifier, the new one is the more common DC supply from external, plug-top adaptor). Switching on the power to the QBox produces very high error rates on the DSL, bad enough to affect service, even though the connected PC is not switched on.
Do all QBox supplies behave like this, or did I just get a bad one? The unit has no manufacturer name on the label, just the input/output voltages "85-265Vac 50/60Hz, 7.5Vdc, 2A" and a possible model number "3825A051", though Googling this produces only 12V supplies. The unit bears a "CE" marking, which requires compliance with EMC directives. It was sold in the UK, but with a Euro-style power connector.
Can TBS provide any advice on curing this problem?