Found the Reference Manual:
http://www.dovado.com/images/Firmware/TINY_AC_Reference_manua80X.pdf
Yes very limited. About the only thing of some possible use is the "data use notification"; just a notification and not what I would deem QoS at all.
Router is not (as can be expected) in the DD-WRT database.
No Sections directly addressing QoS.
The Router does have MAC address control so you could enable or disable individual devices especially if children are involved and not old enough to spoof the system. Did not note any parental control screens for days/hours of use. Would probably limit all users anyway....
Section 3 - System mentions User priviledges via Section 3.7.1 No screens to show what you can control per se.
All I can suggest is to perhaps set up some family/user rules regarding online use. Use the router as best you can to monitor and enforce those rules. Probably only effective if younger kids are involved.
If the situation is serious enough and your use/work is being degraded then a different router is warranted. Read some reviews and then go to the manufacturer's websites and find the appropriate User Guide/Manual. Look through the configuration screens regarding QoS, priviledges, etc.. You may be able to identify a router that meets some of your requirements. Note: Do the best you can to look at documents on manufacturer websites. Starting to see more "mis-leading" (being generous there) links to dubious sites offering user manuals and guides.