Shelly support group (English Version) | Update 2: After some struggling attempts to get the Asus to work I sold my Asus routers and got a Ubiquiti UniFi Dream router and some
Home network design : r/Ubiquiti
UniFi Dream Machine review
Setting up home phone, internet, and TV in Germany | Expatica
UniFi Dream Router - Ubiquiti Store Europe
Build a PC for WI-FI router Ubiquiti UniFi Dream Machine Pro (UDM-PRO) with compatibility check and compare prices in Germany: Berlin, Munich, Dortmund on NerdPart