I'm going with no and then suggest you put the Xbox in the DMZ entry of the router.
Hey,
So I have an issue with my router Thomson TG789vn. Apparently it´s not compatible with a certain game for some reason because it blocks online functions within the game even when having the ports forwarded. So I read on a forum that some guy called his ISP to get a single port "bridged"... here is exactly what he said: "Finland here and I had to contact my ISP to bridge one of the ports on my router. Now it's working like a charm." I can also add that he has exactly the same router as I have.
So I just want to double check, is this really possible just by making a phone call to the ISP, just like that? Also, what does this mean exactly? How do I know which port to bridge? I guess it´s the port my computer is connected to?
Any help is really appreciated, I´m so confused here!

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