I was wondering does anyone know why DrayTek hasent moved over to using simultaneous Wifi 5.8ghz and 2.4 ghz?

I have some devices which use each but with selectable i can only use one or the other??

any ideas why they have done this?

I think I've seen this question before, and the answer was that on products that don't offer simultaneous 2.4 & 5 that it is a restriction of the componenets and chips used.