Problems with high ping when someone is using my internet !

Windows007

Commendable
Apr 19, 2016
38
0
1,530
Hi . I am playing online game called league of legends . When I play this game I usually get 60-70 ms which is OK . I have 2.5 Mbps download speed and I have 0.4 Mbps upload speed . When my brother start watching YouTube videos on Tablet I get 150 ms ping ( he is watching on 240p which is really low quality ) . YouTube videos is using maximum of 300 kbps and my online game is not using more then 50 kbps . I wonder why do I have so high ping when someone else is using my internet . I am sure that this is not anything to do with my download speed because I have good enough download speed and probably this is not causing the problem with high ping .
My question is does the Upload speed have to do anything with this , if so please tell me , or if it is something else please help me solve this problem .
Thanks for your HELP guys !!
 

Windows007

Commendable
Apr 19, 2016
38
0
1,530

Quality of service can help ? Can you tell me what can I do with QoS ? I am using TP-Link 300M Wireless TL-WR841N router.