Need "turnkey" setup for migrating iCloud on NAS (Asustor AS5404T), including Time Machine

Big ask for a forum question. If you are not pretty technically competent and able to manage the security issues around having your NAS open on the web then either get help or get reading. There's no Turnkey solution unless you're going to pay someone for ongoing management of your home system - you're going to have to understand this stuff.

However, here's a few questions I'd be asking if I set off down this route:

1. does your NAS support Time Machine?
2. does your NAS have a dynamic dns function/app/service so you can set up access to it from anywhere
3. if no DDNS, will your ISP give you a fixed IP address for your iCloud service. They'll probably charge you for this as a business service.s
4. Have you got enough upload speed on your home broadband? When you're downloading from your NAS over the web (i.e. away from home) it's download on your phone but it's upload on your home network
5. does your NAS provide a VPN service
6. does your home router provide a VPN service and has it got a proper firewall/NAT service. If it's the ISP's standard router then you'll be buying a new one.
7. How many security advisories a month does your NAS provider put out?
8. Are you OK setting up Subnets on your LAN to make sure the NAS and its web access doesn't open up the rest of your LAN to outside threats
9. Are you absolutely certain that you know enough about the security requirements and configuration of your NAS, your Router and your LAN to cover all the threats that a NAS open to the web will be exposed to
10. See 9
11. See 10

If any of that scares you a little bit then good - cos giving a NAS unfettered access to the web is a dangerous sport. Why do you want to do this? iCloud isn't great but it's bloody cheap and sort of works across the Apple garden. Your ISP might offer a cloud service which will be safer and easier than your home NAS. There are other cloud providers out there too. If your main reason is "I've spent £xxxx on this kit and I should be using it" then it's not the best reason IMHO.

Good luck!

So, in addition to what Zurarczurx has mentioned - Asustor seems (like QNAP and Synology) to offer the kinds of apps and services you need to do what you want. It won't be iCloud, but you can probably set up a Notes Server, etc...but also consider:

1. A homegrown mail server and messages server is non-trivial. You may need your own domain and a 3rd party SMS service.
2. To do what you want properly, you will need to set up a DMZ and likely need to isolate most of the services from each other. Now you are talking about multiple VMs or more likely Docker containers in the NAS, plus a virtual switch infrastructure to control service communications. An "enthusiast-grade NAS at entry level pricing" like the AS5404T probably doesn't have the juice to be the container station you need. That's getting into Small/Medium Business or Enterprise grade territory, not Small Office/Home Office.
3. Your offsite backup plan will probably involve something like Backblaze or one of its competitors, or a raw Amazon S3 bucket system - at additional expense. Not huge, but in the 10's of $$/month, which does add up.
4. Oh, and if you really want to access from anywhere efficiently, then you probably need some custom DNS configurations backstopping your DDNS (not to mention supporting the email server for DMARC, DKIM, and SPF), plus content delivery to the edge, so also Cloudflare or something similar.

Oh - and you'll need another NAS to backup the current NAS and, if you're really going to replicate iCloud, it really should be offsite - so you'll need to replicate your system somewhere that's not your home.

OK - that's good to know. Bit of background: I use QNAP as a home server and TM. It's firewalled from the web and I do updates manually. About 2 years ago QNAP NAS's were attacked a lot and at one point QNAP put out an advisory recommending all devices be taken off the web and the admin accounts replaced/deleted as the main way to protect them. This is a company that sells its stuff as small office web and mail servers and they offer a cloud service that, in theory, does everything you want to do. Imagine if you've just invested in all that and they tell you to go off-air indefinitely until they push updates. I don't think QNAP are particularly crap, I think that these things go round and come round, particularly for web-facing "amateur" kit (no offence intended). Synology were hit a while ago too. I've no idea if Asustor are vulnerable or what support they provide. If I were you I'd lurk on their forums/support boards to see what the views of the users are regarding their Cloud/VPN/DDNS/etc. products and how good a support/ticket system they have before you commit. You might also tap your support network for their views on replacing your NAS's code with one of the free open-source products.