My fear but not confirmed! The installation went smoothly with the installation key and everything worked - almost instantly - perfect. Even the so often criticized "weak signal" I can not confirm. For me, the 904 runs clearly better than the 803 and compared to a 1 & 1 Fritz box with my mother I find the Vodafone even better. Only when adjusting settings I imagined - as for new installations halt usual - itself a leg. So I imagined things that turn blocked other features --- you should just already know what you do there adjusted (-; but Quick helped me the hotline and corrected my experimentation at the right result..
If one considers that one ebay for 30, the box at eg - thrown at Euro gets and comparable FritzBox around 100, - Euro and far more cost ......... the xDSL 904 is perhaps a tip / a ??? cheap alternative I think, yes!
Conclusion: Much is bitching about the box, but I can not confirm the many criticisms - for me it is running and I would join me again !!! Partially run with me even 6-7 devices simultaneously over (PC, smartphones, printers and televisions) ........ easily!