One of the two ways to update software is to put the b2.tar.gz file in the root of a USB disk and run the SW Upgrade command (Maintenance menu). My personal practice is to never update to newer software without saving a copy of what I was running, just in case the new software does not perform up to my expectations. The problem with the Web Upgrade command is that it blows away your old software and doesn't give you a copy of the new software to save.
The Latest Software page on the Brennan website has links to some of the previous software versions. If you know which version was working for you, you can download one that is the closest. However, some of the past versions have problems that were fixed with subsequent releases. By demonstrating that the DLNA feature worked on version X, but then did not work on version Y, it will help them to find and fix the bug in a new release that will hopefully have all the problems fixed.