FYI for anyone running really old hardware that is not running DSM 6.2.4 (the last versions of DSM 6) you will no longer be able to download old versions of DSM and other packages (even through the Synology update center on DSM) due to a licensing dispute of AAC audio
Luckily DSM 6.2.4 does not look like it will be EOL’d so thats good for most people!
If you are effected you probably will want to download the applicable files and save them off somewhere just in case you need it.