Mebbe someone "still in the game" will offer more than an old dino....but there is a LOT that happens on your device at the NIC, TCP stack, etc. that could be the culprit....something misconfigured at the router/switch....
If none of that makes sense....good....yer not a geek Baz
Wait fer Scott or Steve or ????
My last corporate gig...5k VOIP conversions...I don't play dat no mo'....
T-Rex