Grinster67 Yes I have these issues too when downloading with just my browser (Firefox), especially with the larger downloads of 8~15 GB. Along with the download speed often going down until it's just a few Kb/s. It's been an issue only with SLR for the past year or so.
The only way that seems to be working better for me is by using jDownloader, which has a handy way of monitoring the clipboard for links to download. However SLR recently changed their download links so at least in Firefox it's no longer possible to right-click it and do "copy link location"... Annoying but if you know how to get to the actual download link from the page code you can still copy it to get it into jDownloader, then even if it stops partway it'll be able to resume.
Do keep in mind the download links expire over time so don't bother adding tons of scenes, only queue as much as what you're able to download that day.