was suggested here to get a vigor2710ne, awesome little router hasn't lost a sync yet so cant complain there..
seems to be when a lot of lan traffic is going around, pings go insanely high, starting off at about 30 or 40ms pings direct to the router, going up to 400+ if not dealt with, not quiet sure what causes it..
it seems to build up to a point and then just start hyping pings, even when the traffic is routed via a separate switch.
we have a second wireless ap (old dlink) to cover the whole house, so as a test i turned the wifi off on the vigor for a few days, this gave a slight improvement, however that may have just been a lack of copies for those days..
upon removing the cable for a few seconds, the router lets down its guard and pings drop back down to 1ms or so again, as where they should be, this is fine for the next hour or so and then it will start crawling up again.
this issue becomes even worse when hosting lan partys (one link from the draytek to the gbit switches for that) within a few mins the pings will spike back up and sit above 500ms to the router until the rest of the network is blocked off again..
had an issue when i first got it where one of the firewall features was blocking wifi traffic from getting to the lan (not wireless isolation however) so i get the feeling its the same case with this..
hopefully some of the more experienced people here with drayteks will have seen this issue before.. still learning how this all works, the whole object groups system is just so much different to the old dlink.