02-02-2021, 11:29 AM
This is what I found online.1. Get putty ready2. DSM7.0 opens Telnet and SSH3. Use puTTY to connect to DSM7, enter the user password, and enter the following command code:vi /etc.defaults/VERSION4.Overwrite VERSION content:majorversion="6"minorversion="2"productversion="6.2.3"buildphase="GM"buildnumber="25426"smallfixnumber="0"builddate="2020/07/01"buildtime="06:24:39"5.Reboot the machine6.Use the Synology Assistant to find the machine7.Install DSM 6.2.3（At this point, the upgrade will prompt an error, don't worry, because at this point, Telnet port will be opened, and only after this step, can port 23 be opened, repeat point 3, but the user name: root password is: 101-0101）8.Just install 6.2.3 again. It is recommended not to keep the configuration (the file will not be lost), and DSM7 has been successfully degraded to DSM6.2.3Here is a link: https://emby.media/community/index.php?/topic/89848-tutorialdowngrade-from-dsm-70-to-dsm-623/Also similar instruction on Reddit herehttps://www.reddit.com/r/synology/comments/iyr2ct/downgrade_dsm_70/I hope this helps.