Just to update on a problem I thought fixed in a previous post:
http://www.forum.draytek.co.uk/viewtopic.php?f=2&t=15706

The newest 3.3.5.1 f/w had the very strange effect of losing the Wireless LAN entry on the menu, so I couldn't access/change any settings (the wireless appeared to still be working as per its original settings though; I did have some later connection intermittency issues, but probably coincidence...).

Thought I'd fixed it by reset to factory settings and recreate settings manually (I originally used the .all file for upgrade). However, when I later turned the DHCP server on, the menu got irrevocably lost again. And I couldn't even reset to factory settings without a re-flash; if I tried from the menu, it just paused for a second and then switched the check-box to "retain current configuration". Very strange.

Long story short: reverted back to 3.3.2 (via .rst f/w file) and all good in the world again. If anyone thinks I should raise a formal bug, let me know where... I was using a PPPoE connection to my separate ADSL modem, though guess that's the norm for a 2110Vn.