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 the XS4ALL recommendations and some good reading of Roel Traag part 1 and part 2. Cisco examples at KPN forum. Improvements; use PIM to make to more clean.