We have a Draytek 2860, 2 x AP900 and 3 AP910 access points. The plan is to use central management and have this working on 2.4GHz. However there is a footnote in the 5GHz config which states:

Note : 5G SSID Configuration only work with VigorAP800 v1.1.1 and newer APM Client.

When you finish is shows 5GHz as disabled.

How do you get it to work the way you would expect?

Your post prompted me to try this with my 2860n+ and single AP900. It seems to work fine, the 2860 reports the AP900 as being version 1.1.6. Both 2.4 and 5GHz bands are working. I guess that doesn't help you much, sorry.

the two AP900 are on 1.1.4 and the three AP910C are all on 1.1.3.2. router is on 3.7.4.2. trying to push out 5GHz and shows as disabled.

Any reason you don't upgrade the firmwares? http://www.draytek.co.uk/support/downloads