Quite a lot of the Zyxel
modem and router range support Media Bandwidth Management - they can throttle the bandwidth used depending on the traffic/IP/port/etc applicable to WAN/LAN/WLAN independently on a Priority or Fairness based model.
I use it to give priority to WLAN traffic and also throttle my downloader pc when there's HTML/email/etc traffic happening.
Otherwise, there is also cFosSpeed
which I've used for years. You can install it on all PCs and it will co-operatively prioritise the bandwidth among them giving P2P and other bulk protocols a lower priority. It can also do online budgets based on time or volume, traffic analysis, usage graph and prioritise to favour ping time or bandwidth.
Personally, I think it's a great program and it certainly works for my network setup but you can try it for free for 30 days to see if it's suitable for your circumstances.NOTE:
I'm only a happy user of cFosSpeed, not in any way associated with the company. I got my license for free, (by providing traffic data for my hardware/ISP), but I also bought another license.