FAIRY lights on Christmas trees could cause slower broadband speeds, regulator Ofcom has warned, as it launched a new app to test Wi-Fi in homes. The watchdog estimated up to six million homes and offices could improve their broadband connection, saying wireless networks are often not set-up correctly or suffer "interference" from electronic goods including baby monitors and microwave ovens - and even festive fairy lights. The free Wi-Fi Checker app, for smartphones and tablets, allows homeowners to test the quality of their internet signal and suggests ways to enhance it. Ofcom also releas[...]