Just wondering if Plusnet are throttling/limiting downloads on certain platforms? For some reason my Steam, Origin, and Battle.net download occasionally seem to cap off about about 2.5MB/s, well below the 8MB/s I normally get if I download from the web.
Speedtests show me getting my full 72Mb/s speed so there is no issue there, and if I was to download something in Chrome I get around about 8MB/s.
The only explanation I can see here is that there is some sort of limit being placed on these programs downloading.
For what it is worth, I have not used the speed limiting options built into steam or battle.net.
Plusnet don't limit or throttle anything, I hit my top end in steam for my connection when i downloaded something earlier, does seem weird that your able to download in a browser at max but not the programs you mentioned.
i would say limiting options but you say they are not in use so i can only think that it could be server related I know in steam you can pick which server to download from, maybe try a different one see if that makes a difference, i can't speak for Origin or battlenet as i dont use them.