WAN Access other than BubbleUPnP Server

[Mike48]

After upgrading my DS414 to DSM 7, I was unpleasantly surprised to find that BubbleUPnP Server no longer works, nor is BubbleSoft planning to release a DSM 7 package. The suggested work-around is to install BubbleUPnP Server under docker, which I know little about and seems to involve a level of complexity I prefer to avoid.

Are there recommendable alternatives for WAN access of MinimServer? The hope would be to run as BubbleUPnP Server did under DSM 6 -- offer password-protected access to a UPnP/DLNA music server. And be installable via a standard Synology package for DSM 7.