@David-TP By some chance miracle I have got my Deco system back up and running after many hours of trying over the last week.  I thought I'd give it another go but this time I did not connect the ethernet cable until AFTER it said no internet/ethernet cable connected.  This is contrary to the instructions in the app which tell you to connect and power up the internet/modem at the SAME time as powering on the Deco main unit.  It's been so stressful that, like HarryTP, I will be very hesitant to ever click 'update firmwear' in the furture!

  @HarryTP i have the same problem. Firmware update = no DECO