For the longest time I was searching for a fix for slow steam downloads compared to my actual ISP speeds. My actual download speeds using speed test was at or around 550 MPS but on steam I was only able to reach anywhere from 50 to 100 MPS. But I kept searching online and finally found a work around. The fix is to add a line to a steam config file using nano or any file edit app. So.... step 1 use command below to edit file and then enter line step 2 save a close and restart steam or you machine.
- sudo nano .steam/steam/steam_dev.cfg
- @nClientDownloadEnableHTTP2PlatformLinux 0
And this worked for me and it will not break steam or your OS.