I did some experiments in the past. The nicer option I could find was enabling webdav API on the hosting side (it was an option on cPanel if I recall correctly, but there are likely other ways to do it). These allow using the webserver as a remote read/write filesystem. After you can use rclone to transfer files, the nice part is that rclone supports client side encryption so you don’t have to worry too much about other people accessing files.

Could it be that the domain name has both IPv4 and IPv6 and depending on the network you try to reach one or another? Wireguard can work on both protocols, but from my experience it doesn’t try both to see which one works (like browsers do). So if at the first try the dns resolves the “wrong” IP version, wireguard cannot connect and doesn’t fallback trying the alternative.

QNAP sells extensions unit https://www.qnap.com/en/product/tr-004

They usually connect with USB (at least for home grade devices), but my understanding is that they are not seen as block devices so the nas has access to all the single drives like they were internal.

Back to the days I was fixing a lot of computers of friends and relatives, my Swiss army knife of Linux was https://www.system-rescue.org/

Very lightweight but with a full set of recovery tools. I’ve tried it recently and I still find it up to the expectations.

I’ve also used a fair amount of https://clonezilla.org/ to (re)store images of freshly installed OSes (mostly windows XP and 7 to give you an idea of the timeframe) for people who I know would have messed up faster.

A lot of technical aspects here, but IMHO the biggest drawback is liability. Do you offer free storage connected to internet to a group of “random tech nerds”. Do you trust all of them to use it properly? Are you really sure that none of them will store and distribute illegal stuff with it? Do you know them in person so you can forward the police to them in case they came knocking at your door?

Yes, you can do it on your server with a simple iptable rule.

I’m a little rusted, but something like this should work.

iptables -t nat -A PREROUTING -d [your IP] -p tcp --dport 11500 -j DNAT --to-destination [your IP:443]

You can find more information searching for “iptables dnat”. What you are saying here is: in the prerouting table (ie: before we decide what to do with this packet) tcp connections to my IP at the port 11500 must be forwarded to my IP at port 443.