Hello,
The error obtained is "server unresponsive", which could be due to network issue and may resolve by retrying. You may like to run AUSST in "Incremental Synchronization" mode (that is option 2) to avoid re-downloading files that are already downloaded.
If you still face this issue, after retrying couple of times, we would need DLM.log to analyze this issue further. Please use steps below, to create detailed DLM.log
Please create asu.trace file at “%temp% “ on Win machine, where AUSST is running.
Then run AUSST again and collect the DLM.log found at "%TEMP%\AdobeDownload"
Thanks