Update:
I was able to run a few more tests last night, I found out that it happens on both Xbox's. Which ever Xbox I turned on first had port 3074 and the Xbox I turned on second would have a random port associated with it. So both Xbox's are having this problem.
I also confirmed the answer to this question earlier,
"Why doesn't all the out bound traffic have the priority setting I have entered in my GF rules? because they were UDP and not TCP???"
Answer: I did not have "both" selected for the protocol in the GF rule.
Okay so this what I did last night and the results:
In network settings in the dash board I reset to factory defaults on the XBox = no change.
Disabled port triggering under "special applications" = no change.
Disabled UpnP= No change.
So for what ever reason my router will not let both Xbox's use the same ports. I also think I found an easier way to check what port each Xbox is using for gaming through the dashboard. However I would like to see this happen a few more times before I commit to it.
Maybe someone else can give it a try and confirm or deny it.
Turn on Xbox, sign into XBL and when on the dash board select "settings"=>"system"=>"Console"=>"system info" and in the top right corner it should tell you your IP and what port number it is using for XBL.
Anyway, so right now I have a GF rule set up to cover all ports for each Xbox until I/we get this figured out.
This weekend I am going to see if it happens with GF disabled and if so I will save my config file and do a factory reset on my router to see what happens.
Any other ideas?
Also, could my modem be causing this problem?
Its a Cisco DPQ3212, DOCSIS 3.0 cable modem.