In the end, I configured as Access Point "AP" - which also suits me and gives me bandwidth without loss of throughput. This allows me to have a 2nd to my access point a network in the same ranks Address (useful to enter UPnP devices).
The mode "Router" also works very well and also has access to all primary functions of a router (filtering / forwarding / DHCP / etc ...).
I did not test the last mode "WISP".