Only the concept of remote access via "Quick Connect" is (for me) is inconclusive. For one (but not all) required for some features additionally a DynDNS account (Selfhost.de or no-ip.com offer this still free), so that the appropriate services are working from the Internet.
Who calls a UPnP router fähighen its own, can let it automatically open the necessary ports on the DS. For safety reasons, however, I advise against it. To check what ports need to be open for ever, but that is quite useful.
For me, the DS is used for both Windows Linux and Mac machines as a backup destination. The Time Machine support work clean, under Win & Linux I access via CIFS to it, both runs without problems reliably for weeks.
Updates appear regularly and are to be installed with a single click. Even after a power failure, the DS ever came clean up again. However next purchase is a UPS that is supported by Synology.