How can I "allocate" internet bandwidth to a specific app or device

So, I need to download a huge sized game (GTA 5). Its size is about 70 GB, but as my internet connection is not stable (sometimes fast, sometimes slow) and sometimes is very low, I need a way to "allocate" like 0.5 MB/s (not 0.5 Mbits/s but the effective download speed) to my main computer to me be able to search and use the internet, and the rest go to the other computer, to the download.

Is that possible? if yes how can I do it?

Edit

I will be more specific:

So, right now my download speed is 1.2MB/s, so I want 0.5MB/s go to my Main Computer and 0.7MB/s go to the other computer that is downloading the 70GB game.

Other Example:
If I had 3MB/S download speed, 2.5 would be to the download and the 0.5 to my main computer...

But if my download speed was like 350KB/s all bandwidth would go to my main computer...

Edit

My router does not support QoS and I guess i can't install dd-wrt or openwrt, because the router is from the ISP and it receives the internet via 4G/3G

My router: Huawei B593s-22

DiogoSaraiva

Posted 2016-06-07T13:34:36.917

Reputation: 307

@Nzall my router do not have QoS... – DiogoSaraiva – 2016-06-07T13:48:48.207

1If your router does not support QoS, you should mention that in your question because it's relevant. Actually, just edit your question to include the specific router you use so we know what you can and cannot do. – Nzall – 2016-06-07T13:50:58.373

@Nzall sorry i din't knew that was relevant, but updated my question now... thanks – DiogoSaraiva – 2016-06-07T13:53:11.653

Since QoS is not an option, what method are you using to download the game? Steam? the Rockstar desktop client? another DRM platform? – Nzall – 2016-06-07T14:32:23.950

@Nzall I'm using the Rockstar one, the social club i guess. Not steam... thanks – DiogoSaraiva – 2016-06-07T15:12:15.593

QoS on his router is not relevant. QoS on his router won't affect what packets his ISP puts on the wire to him. – David Schwartz – 2016-11-07T19:47:02.380