I'm continuing my push away from big tech and want to upgrade my storage and backup solution so I'm not using their "free" cloud stuff or at least not reliant on it.

Requirements:

• Remote/mobile access: meaning I still want features like if I pic/screenshot on my phone it uploads it to the NAS like I do with a cloud now.
• Caveat to remote access: not reliant on third-party servers (excl. a dynamic DNS service)
• Automatic offsite backup -- I'm fine with it backing up to a hostile service, as long as it's encrypted and I control the keys

Bonuses:

• Plex Media Server support
• Dual hard drives: I'm not convinced this actually buys me much particularly with an offsite backup, but it lets me get more space on the cheap too.
• The more configuration the better, but I don't want to have to build a "server" from the ground up either for this.

Synology seems to be the closest I can come up with, but I'd love to save some money and/or learn more, so I figured I'd ask. There seem to be people here who would have experience with these things.