Thank you for your replies. I'll report if there are any solutions.

I think you don't have the same router. It's the VR2800 v<--- Is there any official TP-Link Support? By the way, I now could see the log: 2016-01-01 01:00:33 [5] VoIP: DECT base firmware build time...

This is the software-version the router was delivered with. Therefore I can't downgrade or something like that. Maybe the TP-Link Support Team knows the answer.

Model : Hardware Version : Firmware Version : ISP : Hello everyone, hello TP-Link team, I bought the new Archer VR2800 v. From the functionalist view, I'm very happy with this router, but sadly it...