The Fritz!Box 7390 has issues with VAS and icmp forwarding, secondly I feel like the performance of the router is not meeting it's expections, yet no verification possible yet. Hence the switch to a FreeBSD based router/setup. First of all homework. Read [https://www.xs4all.nl/service/diensten/internet/installeren/modem-instellen/hoe-kan-ik-een-ander-modem-dan-fritzbox-instellen.htm the XS4ALL recommendations] and some good reading of Roel Traag [https://mijnglasvezelverbinding.nl/tv-internet-over-dezelfde-netwerkkabel/ part 1] and [https://mijnglasvezelverbinding.nl/tp-link-tl-sg3210-mac-vlan-configuratie/ | part 2].