Maximum Concurrent Downloads

[Noriller]

Describe your suggested feature

Sometimes on crappy connections, multiple concurrent downloads make none actually download and all fail because of one error or another. So, an option to be able to set how many concurrent downloads to use can be used to make sure you can download what you want.

Other details

It could be maybe a "focus download" option that makes you download only one at a time, instead of one per source.

Acknowledgements

• [X] I have searched the existing issues and this is a new ticket, NOT a duplicate or related to another open or closed issue.
• [X] I have written a short but informative title.
• [X] I have updated the app to version 0.16.4.
• [X] I will fill out all of the requested information in this form.