Can't see multiplayer

Thanks @ ScottMDA for your reply!

We checked the Xbox gaming settings , and after using the “Fix it” option our NAT type is “Moderate” and server status is “Connected”…
However: unfortunately still no other players visible when relaunching the game…

Has anyone got an idea:

if NAT-type “moderate” should be enough to enable the multiplayer-option?
if not, how to change it in “open” (i often saw this in other discussions about Xbox live-gaming problems, but don’t know how to change is; everytime after the “Fix it” option, it’s on “moderate” on our PC)…

Regards,
Jos