v3.8.5 also breaks multi-nat DMZ.
The outgoing IP address of a DMZ host is the NAT pool address.

smwardle wrote: v3.8.5 also breaks multi-nat DMZ.
The outgoing IP address of a DMZ host is the NAT pool address.

Typically I wouldn't expect [NAT] > [DMZ Host] to fix the outgoing address, only forward all incoming ports. Could you try setting up a policy route to do the address mapping as per this guide?
Policy Routing - Address Mapping

Multi-NAT DMZ has been able to set the DMZ outgoing address in every Vigor router I've used until installing v3.8.5 on the 2860.

See "How do I fix a one-to-one IP Mapping for outgoing traffic?" here:
https://www.draytek.co.uk/archive/kb_vigor_multinat.html

or here: https://www.draytek.co.uk/support/guides/kb-vigor-multinat-fix-outbound-ip

Tried 3.8.5 v4 on my 2860 connected to BT infinity.

After updating the firmware I found the router went into a cycle of training / disconnecting so had to revert to the latest UK version.

The next day DLM reduce my line from 74 to 59 meg. Damn!

Yes

UK still recommened 3.8.4.6 BT. I think 3.8.5.x has a lot of issue at present.

V3.8.5 has now made it onto the UK web site . I did a binary comparison of the 'flavour' I have installed (VT3) and it is identical.

The Release Notes, on the other hand, have been rewritten...