The router will reboot seemingly at random when upnp is on. now turning it off stops this but i don't see that as a fix by any means. i do play a lot of computer games and upnp is kinda essential to them running well online as far as i can tell.

Does anyone know anyway i can keep upnp on without it rebooting the router.

Latest firmware 3.6.6.1 is here (check and the released notes)
ftp://ftp.draytek.com/Vigor2850/Firmware/
you can also try a backwords firmware, one of them should work with out problem the upnp or ask the support for newer beta
how ever changing firmwares (upgrade/downgrade) you need to use the *rst* file extension to avoid bugs conflicts

I'm on the latest driver, would rolling back not introduce volubilities? i will have to go back to V3.6.3 i think that was the one i had before my first firmware upgrade.

Okay rolled back to 3.6.3 see how that goes.

the 3.6.3 had some wifi issue with android phones causing reboots sometimes
variability it may be issue because with 3.6.6.1 the fix was for open sll so if you not using it disable & the vpn, VPN and Remote Access >> Remote Access Control Setup (untick all)
also at maintenance >management don't enable https for wan
You can ask the support if they have latest beta (should have the open ssl fix)
http://www.draytek.co.uk/support/techquery

Okay so i'm still getting the reboot on that firmware, will have to contact them about this. It seems to have been an issue for a while, most likely due to it being an unused feature for most people to do it's possible security risks.

I've gone back to the latest version also using the rst file to clear any previous configs (i assume that is what it does).

Thanks for the help and other ideas would be appreciated

I am not experience with consoles (not use my ps3 for very long time) BUT other isea is to try port forward & close upnp, maybe the ports the console using?
http://www.draytek.co.uk/archive/kb_vigor_portforwarding.html
but first set a static ip at the console & at the draytek
http://www.draytek.co.uk/archive/kb_vigor_dhcpfix.html

here an old example with a PS3
http://portforward.com/english/routers/port_forwarding/Draytek/Vigor_2930n/PlayStation_Network.htm