So far, the biggest map I have tried is Spain and that downloaded without any issues. However, in my place, it wasn't happy about mobile net. That's not surprising since we have a place/operator combination that resets connections quite frequently. Worked fine on WiFi.

One suspicion would be that maybe phone enters a deep sleep while downloading leading to "Connection closed". Namely, I have not used any keepalive and the both of my devices (N4 and OPX) worked just fine to my surprise. So, I didn't even look into keepalive locks. Maybe its not working for you.

Try to put your device on charging and download then.

On the technical part: many of the databases are split into several parts. As long as you see INFO messages on the main screen with "File downloaded" you are progressing even if after restart of the download the apparent size remains the same. So, you should be able to download by these batches... However if you are stuck on some bigger file (larger than 200-300 MB) then it will be trying to get the same file again.

Let me know if putting on charger helped. If that''s a problem, I'll add keepalive lock and we should be OK.