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I'm using a raspberry pi 2 model b running Ubuntu core, and a TP-Link TL-WN821Nv3 USB WiFi adapter, which has a maximum speed of 300mbps/37.5mBps, and a Samsung charger which supplies 2A (lower than the recommended 2.5A), Camera module is plugged too.

here are the results, ran from and with an open ssh connection:

user@localhost:~$  speed-test
       Ping   3600 ms
   Download   1.1 Mbps
     Upload   0.4 Mbps

I did a little test that didn't hands-down confirm this hypothesis: I plugged in mouse, when running the speed test this time, I kept moving the mouse held space key down periodically (so not to bottleneck with CPU/USB-controller), to ensure they're drawing current (100mA minimum each):

user@localhost:~$  speed-test

       Ping   3600 ms
   Download   1 Mbps
     Upload   0.3 Mbps

download and upload speed decreased by 0.1Mbps.

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    The less power available to each USB-connected device, the more problematic/slow they'll become. Get a better power source. – user96931 May 2 at 19:25
  • Your keyboard and mouse will draw a maximum of 100mA, not minimum. The difference is low and may be attributed to chance. The ping value is very high. – RalfFriedl May 3 at 5:11

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