Pretty sure I've updated since then but will be sure to check the version. First Cisco now Owncloud it's dangerous out here.

For file syncing, I would highly recommend owncloud over next cloud for self setup. I've tried next in a few instances and they are much more feature rich but not nearly as reliable in my experience and requires more maintenance. Owncloud is simple maybe even too simple for you, but sync features for me work out of the box. For computers just download the app. Point it to your server and you're good. For mobile there's an app for it though it is more limited than the desktop app/next cloud. You can look at videos too and make your own decision but that's my 2 cents. I currently run it off proxmox.

For docs, I've also run into issues with Joplin and haven't moved from onenote yet. I tried orgmode but again that requires another technology stack with either git or synching and emacs. The best solution I've used so far is obsidian (idk if it's FOSS) with synching but it's all markdown so not easy to just edit unless you learn markdown.

Truly I feel your pain. I work a full time job as a carrier network engineer, and currently working on my CCNP while taking a term break from night school. Time is precious, and unless I'm learning something that is going to make me more well rounded as an engineer or that I am flat out interested in I want to minimize it as much as possible. I would not put troubleshooting the peculiarities of Next Cloud in that category haha, but maybe you do.

Oh nice. For mine personally I have a proxmox server and pfsense is one of my vms. It's not my edge router though because I am not passing through the nic it is using directly to the firewall so technically it would be proxmox virtual switch on the edge which I don't inherently trust so my provider router is at the edge and I just port forward any ports for services I need. This can all be simplified of you just get a physical appliance from netgate website lol. I'm planning on doing so myself in the near future. It's a great product though software wise once you get the hang of it it's fairly straightforward. Fortigate also has home equipment but I think it comes with license cost. I'd look into it if you have money to spend because they are another industry leader.

I've heard good things about TP Link WAP as well. They have some that support 2.5G/Wifi6. I like pfsense if it is available in your country/budget for firewall. I use a virtual appliance but it's essentially the same thing software wise. It has a bit of a learning curve and but it's a very common enterprise level firewall so the skills you learn will be transferrable not just to work (if you work in IT) but also to other firewalls like fortinet, Palo Alto, etc. because the fundamental firewall principles are the same even if the GUI and specific features are not.