I tried Nextcloud a while back and was not impressed - I had issues withe the speed of the Windows sync that were determined to be "normal" with no roadmap to getting fixed. I'm now planning to move off Windows desktop so that won't be an issue - so I thought I'd try again.
I went to nextcloud.com, clicked on Download-> Nextcloud server -> All-in-one -> Docker image - Setup AIO. This took me to the github README at Docker section. I'm already running docker for other things so I read the instructions, setup a new filesystem for my data directory and ran the suggested docker command with an appropriate "--env NEXTCLOUD_DATADIR=". I'm then left with a terminal running docker in the foreground - not a great way to run a background server but ok, I've been around for a while and can figure out how to make it autostart in the background ongoing. So I move on to the next step - open my browser at the appropriate URL and I'm presented with a simple page asking me to "Log in using your Nextcloud AIO passphrase:". I don't have a Nextcloud AIO passphrase and nothing I've read so far has mentioned it. When I search for it I get some results on how to reset it, but not much help. I could probably figure that out too, but after reading some more I found that Nextcloud requires a public hostname and can't work with a local name or IP address. I'm already running my home LAN with OpenVPN and access it from anywhere as "local" - I don't really want to create a new path into my home network just for Nextcloud.
I'm sorry - I know this sounds like a disgruntled rant and I guess it is. I just want to check that I'm not missing obvious things before I give up again. All I want is a simple file sync setup like onedrive but without the microsoft.
I'm in the process of (very slowly) migrating my household from Windows to Linux and am currently testing Nextcloud as a replacement for OneDrive. In my case, I set it up using pikapods.com because I want offsite storage. The server part of the setup was incredibly easy because the host did all the work.
Getting my Linux client setup was kind of a pain (especially compared to the Android and Windows clients), but everything seems to work ok so far. Of course, I'm only backing up a small amount of data so far, so I can't comment on the efficiency or speed for a major backup.