To get faster steam downloads in linux:
create ~/.steam/steam/steam_dev.cfg
and add:
@nClientDownloadEnableHTTP2PlatformLinux 0
@fDownloadRateImprovementToAddAnotherConnection 1.0
restart steam, start a download, and you should notice a better download rate.
for me it went from capping at 100mbps to now going 500+mbps like it should.