Ping spikes after downloading

[dark16sider]

I have a Huawei router and when I ever download something, pinging the router through WiFi shows huge spikes and drops. The downloading seem unstable too, going down and up. When I surf the internet it is normal.

I have tried many things to test it. This doesn't happen when using Ethernet. This happens to multiple devices using WiFi. The downloading device is the only one affected and not the others, meaning all the devices have normal pings except the downloading one. This usually doesn't happen to low speed but to higher, it appears over 250 kbps but my downloading speed is way over 250.

Here is an image of pinging. The first part is without downloading, the other part is without downloading.
https://imgur.com/a/fnQXO

 

[jgustin7b]

DURING the download, it is normal for the ping to go high, as the system tries to download as much as possible quickly, therefore using most of your network resources. If you check again about a minute after a download, the ping should start to settle down. If not, you may have a problem.

 

[dark16sider]

DURING the download, it is normal for the ping to go high, as the system tries to download as much as possible quickly, therefore using most of your network resources. If you check again about a minute after a download, the ping should start to settle down. If not, you may have a problem.

I doesn't happen when it reaches the limit it happens when it goes over a fraction of it. This result in the downloading going from the limit to 15 kbps and become completely inconsistent( periods of up and down). This doesn't happen using Ethernet too
and doesn't affect other devices, it only affect the downloading one.

After downloading for 5 minutes the connection just completely shut down. Long connection drops. The straight lines are after stopping downloading.
https://imgur.com/a/U9Vj0