Firefox & Downthemall increase number of segments, maximum concurrent downloads
February 13th, 2016 adminrefer also:
https://bugs.downthemall.net/ticket/1614
This has never been a bug. You can adjust these setting by going into about:config on your Firefox
Then finding
extensions.dta.ntask //for max concurrent downloads
extensions.dta.serverlimit.perserver //for max concurrent downloads per server
extensions.dta.maxchunks //for max segments per download
And setting them to the number you think most appropriate. I used 100 on each of those, but that may be too much for you. Experiment a little bit. You can always lower the settings from within the Down them All interface once you set them really high here.