whats your internet bandwidth? For qos to work well you don't want any bottlenecks in front or behind.
ideally your wifi should work > than your isp bandwidth. if you have really poor connections in parts of your home then it will bottleneck.
to make sure the isp side doesn't bottleneck you will have to limit your connection to 80% or higher if you're lucky.
All buffering has to happen at the router or it can't control anything.
View: https://www.youtube.com/watch?v=o-g2P3R84dw
this router can handle 100Mbs QoS.
openwrt, ERX, or ipfire are the best options. ERX is the least expensive, $50, and works out of the box. openwrt has cake qos which will work better with dsl, you will have to flash a router to get this, speeds will vary depending on the cpu speed. ipfire works with any internet speed and it has a gui for configuring class based rules, which is more optional. ipfire will cost you $250+ for a basic computer to run it on.
class based qos doesn't work that well on < 10Mbs for these specific qdisc. the classless works fine. if your speeds are that low 10 ppl sharing will still suck no matter what. in general you want 5Mbs+ per person using it.
configuring class based qos is fairly difficult. p2p is nearly impossible to do (ipfire tries)
Just adding the akamai network into tier4 alone will help a ton.
you can video streaming services into tier 2.
tier1: voip, acks
tier2: media streams
tier3: default
tier4: downloads, vpn
the idea is if a particular service is running slow you can look up it's CIDR ranges and then add it into one of the tier's otherwise it's in default. if you can identify something bogging down the network then add it's CIDR into tier4.
if p2p is a huge problem you can block the trackers using ipfire. then they can use a vpn which will get throttled very well.