Can't connect to HW2 online services

1. What is the issue?

Game cannot connect to HW2 online services. Even though I’m on XBL without any issues (can create/join parties, etc). And can play Halo 5 MP (specifically, Warzone Firefight and consume reqs), Destiny, and Rocket League.

I’ve tried both the WIFI on my cable modem router (NAT=open), and the LAN cable that I run to a switch which is then hard wired to said router (NAT=restricted). I know the LAN connection works because it’s what I normally use to connect my Mac Pro (and have also used it to connect a Windows based machine).

I encountered this same messages in the Blitz Beta, and was never able to play it. Unless you count the main menu as “playing” :p. The public beta before that I was able to play MP just fine. However, during that first beta I was with a different ISP and had a different cable modem (but I was still connecting to the same switch mentioned earlier).

Plus side? My inability to connect allowed me to play HW2 in the CST timezone at 8pm, before I was actually supposed to have (early) access.

If this is really on my end, I don’t feel I should have to mess with network settings or open ports if other games don’t require such work as well.

2. What platform are you playing on?

Xbox One. EDIT: as I noted in my reply, this problem also occurs on the PC.

3. What’s your gamertag?

kornman00

4. What region are you playing from?

'merica

Thank you in advance!

I finally got around to installing HW2 on my PC early this morning. It too gives me the error about not being able to connect to the HW2 online services. So this feels like a networking issue. What ports does the game use, especially ones that H5 doesn’t (since I can play it without issue, along with Destiny, Rocket League, etc), so that I can ensure they’re open and rule out blocked ports?