Hi,
Firstly, i'd like to confess that I don't actually play ArmA :P
But i've got what I believe is exactly the same issue (DGN1000 + Orange = me :( )and it results in me not being able to use PSN on my PS3 nor play Battlefield 2. Has anyone had any luck in convincing Orange to send another router? 'Cos they won't believe me when I say there's a problem because "websites work so broadband work". The support is terrible.
Anyway, just though i'd say that this problem can't be too rare, the DGN1000 seems to be a pretty terrible router :(