XBox 360 Gaming Problem

[#1]

I've briefly touched on this on other threads, but it's not getting annoying so thought i'd post my own thread and see if anyone can help.
I have a number of friends on my friends list, and;
If Friend A hosts a game on COD4, or is even in a game in PGR4, I can't join to it.
If I host a game on COD4, or am in a game on PGR4, then Friend A can't join it.
All my other friends on my list can join both mine and his games, but we don't seem be able to talk with each other.
I can chat with my friend on a private chat, so XBL seems ok, and maybe it's a P2P between Plusnet and Orange?
I'm on Plusnet (obviously) Pro package, have a static IP, OPEN nat setting, no port forwarding, using UPnP. Have a netgear rangemax router, and am hardwired from XBOX to Router.
I believe he is on Orange, not sure about static IP, OPEN nat setting, using port forwarding, using the Xbox 360 wireless adapter to his Orange provided router.
I've no idea if this is an ISP issue, or router setting (e.g. mtu), or something else. It just seems odd everyone else can join my games, everyone can join his games, but we can't play anything together, certainly not anything involves communicating directly to him. COD4 only works if neither of us are the host, as all data comes through the other player who is the game host. However PGR4 needs to talk to every player so doesn't work for us at all. Which is a pain when 6 of my friends are playing and I can't because this one friend is playing.
I hope you get what i'm trying to say, and will be grateful for any clues or solutions.
Regards
Griff

[#2]

Comments removed due to resolution/response from Plusnet.
Thanks guys.

And any help on my original issue would be great thanks.   

[#3]

Hi Griff.
According to our records you have a static IP
The static IP component is active. The details are as follows: 
IP Address  80.229.***.***
Our radius logs show you as having been connected with the same Ip for 9 days now.
What IP adress is your router picking up? Can you PM me with the details?

[#4]

Quote

If Friend A hosts a game on COD4, or is even in a game in PGR4, I can't join to it.

Very odd, have you raised a support request to XBOX live about this? I'd advise going down that route as they should be able to help you pin down the cause.

[#5]

I've posted on their forums, but not directly to Xbox.
Generally there response is "use a certified router".  However when there are only two manufacturers with around 8 routers on their certified list, it becomes a bit of a pain.
Even though i'm using uPnp, i've added the three xbox ports to port forward to the xbox, and increased my uPnp advertisement hop timeout from 4 to 8, incase it's a network issue with the number of devices.
If that doesn't work, I guess the xbox will have to go into a dmz, and see if that solves it.  With it being an xbox, it shouldn't bee too much of a security issue.

[#6]

i have heard that using both UPnP and also port forwarding can cause issues, it certainly can on the PS3.

[#7]

I'll keep an eye out for that if I have any ill effects.
If I do, i'll switch off uPnp and keep the port fowarding a while.
Thirs will be the dmz option.
All this, just because of issues between two people.

[#8]

Well I switched off uPnp, port forwarded the three ports, and it seems to be connecting to my friend ok.
He did say he changed his port forwarding, not sure if on or off, so not sure if it was me or him that had the issue, but all seems ok so far.

I haven't seen any increase in connection strength in games, or decrease in lag yet on my 360, so don't think the pro package made much difference.  It's pretty much the same price, and although I have a reduction in 20gb download limit, and bigger peak times from my old package, I may just stay with it.

Also, on not being able to access my router remotely, it suspect it's because plusnet's firewall, on 'low', blocks port 8080, which my router is on.  I haven't tested it yet, but it sounds like it will be the issue.