Q: XBOX ONE NAT STRICT with PPPoE ISP

Hi,

I'm currently stationed in Japan and just moved off base where it's been a real pain trying to get my Airport configured correctly for XBOX Live on my XBOX one. The fiberoptic internet I have from NTT (my ISP) is output from their provided modem (it is only a modem so I don't think there's a dual NAT issue) via PPPoE into my Airport. I know the Airport technically isn't listed as a router that supports full XBOX live functionality but I've had no issues in the past, I just can't get the NAT setting to anything other than "Strict" which, though it allows me to play games online just fine, I cannot communicate in any chats or or join any parties. Does anyone know the answer to this? Thanks.

-Adam