Seems to be hit and miss sometimes it works sometimes it doesn't. So any ideas.

Well on any wired pc it's not working yet if I connect via wireless it works. I've looked at the port forwarding rules and they are the same bar the ip address that I use for other devices and they work.

Found the issue it's down to jumbo frames. Disable them it works even though both adartors support jumbo frames it seems to get into a tangle. Draytek supports jumbo frames on the local lan but not of course onto wan. So I guess the packets are being fragmented and then blocked on the return journey back into the network. Only a guess.

Interesting despite jumbo frames being enabled I can access it via ip address rather than url.