Just applied 3.9.3.1 to fix another problem and discovered that Draytek have removed a large part of the Access Point central management making it pretty useless now.
Our AP profiles used mulitple SSID's (pretty common requirement for guest networks, etc) and we used the ACLs as well - all this functionality has gone and what is left is a very basic subset of the config capability now.

Logged with Support and response is "I can confirm that this is due to the firmware upgrade. The ability to manage multiple SSID's was removed to simplify management."
Seems a bit of a retrograde step - anybody else finding this?

It's the same with the Vigor 2862 firmware releases, the reasoning at the time being that adding Mesh functionality required re-organising how APs are managed.

The AP management functionality is being reverted to its previous capability in a coming firmware release. In the meantime, I recommend contacting support and asking for a beta firmware to resolve your issue until that release is available.