hello, so i'm using the "new" archer vr600 adsl/vdsl modem router and  I enabled my QoS in order to fix my ping spikes, which it did, it resolved all of my ping spikes by lowering my upload speed a bit, now I'm paying for 100 download speed and 5 upload speed, without the QoS enabled i'm getting 80-90 download speed and 5 upload speed everytime,

but when I enable QoS my download speeds reduce dramatically to 30 mbps, stuck at 30 mbps no matter what, I checked that in my phone, laptop, and pc, I tested it in 5 websites for speed tests, now is there anything I can do? 

because that doesn't make any sense to get 90 download speed but when using the QoS im getting 30 max.

I just want to mention that I purchased the router 2 weeks ago rly new,

if I disable QoS im getting the full speed I need but then I wont be able to fix my ping spikes without QoS on.

heres an SS to my  settings : 

I put  5 upload speed so I can get 4 upload speed so my netflix/youtube on the tvs won't use a lot of bandwidth so I can have a little space