- forum.synology.com/wiki
- http://forum.synology.com/wiki/index.php/Overview_on_modifying_the_Synology_Server,_bootstrap,_ipkg_etc
- www.synology-wiki.de – there is actually also a German wiki
- www.synology-wiki.de/index.php/IPKG – that’s where and how I got hold on the alternative rsync – once “IPKG” is successfully set up, “ipkg install rsync” will do what it says
- http://www.synology-forum.de
- http://www.synology-forum.de/forumdisplay.html?157-Router-RT1900ac
- https://SynoCommunity.com – are the packages a little outdated?!?
- https://github.com/SynoCommunity
Update 2016-01-27: This article tells you what to do: www.synology-wiki.de/index.php/IPKG. But actually not all steps are obligatory, and that’s a little hard to recognise at first sight.