There's nothing exotic about your setup so as long as you're using valid credentials it should just work. No need to force to SMB1 or use legacy security as long as you're using LE 8.2 or newer as SMB2/3 are supported.
NB: If sources.xml contains Windows smb:\\server\path references I'm not sure how those are interpreted on Linux where smb://server/path is used (backslash vs. forwardslash).
I've moved the thread to the correct location in the forum.
Please provide a Kodi debug log showing a manual refresh of the repo.
If the "not working" TPLINK TN-722 is timing related you might need to add a "wait for Kodi" startup delay - in network settings in the LE settings addon. This just delays Kodi start for 'x' seconds to allow time for slow loading drivers to finish before Kodi attempts to access things on remote shares. You won't see this problem with desktop distro's but LE boots a lot faster and the slow activation of some (mostly realtek and poorly written out-of-tree) drivers can be exposed.
The ProFTPD addon in our repo (services) may support LFTP but no guarantees. If not you'll need to adapt your script to use something like scp or rsync to move files between locations.
You must do special things to your browser and OS then. For everyone else this forum has black text on a pale grey background. There is also no white text in the USB/SD creator app. PEBKAC.
If you enable SSH on the NAS and install the public SSH key for the HTPC user you can use key-based authentication between HTPC and NAS and there is no need to handle passwords or locally mount remote shares. You can create a backup script on /storage using the nano or vi text editors (via an SSH session). Run "crontab -e" to edit the cron schedules for the root user on the HTPC. There are lots of cron HOWTO's around that describe how to set things up - so I won't spoil the learning experience by doing all the work for you 
The main thing to remember with cron is that you need to include the full path to any binaries you execute, e.g. /usr/bin/bash, and the full path to the script that bash will run, e.g. /storage/scripts/backup.sh
Addons are not updated as part of the OS image so Kodi will need to start and then fetch updated addons. Until this has happened things will be a little non-functional. This is how Kodi works - it's nothing specific to LibreELEC. If after a while things have no self-updated there is either some kind of networking issue preventing access to our repo, or maybe something bad in the previous config and you'll need to provide a Kodi debug log for anyone to investigate further.
People give up their spare time to write code. People give up their spare time to create wiki pages. Notably fewer people write documentation than provide code .. such is the curse of most FOSS projects. Feel free to request a wiki account and contribute something back.
We use in-kernel decoding instead of LIRC so you'll need to spend a few minutes adapting configs. The wiki is the reference for how to do it, and it's not that hard (but it's not the same as configuring LIRC on Ubuntu). At the end of the day YOU have chosen to change distro so YOU should expect to spend a little time setting things up again. Please remember that anyone responding to your posts in this forum is giving up their personal free time to offer help. Whinging about everything is not going to inspire them to offer assistance.
Feel free to go and use something else then. One less user moaning about something benefits the project. Whatever works for you works for us.
Follow the systemd mount example in /storage/.config/system.d/ to create a local filesystem mount for the remote NFS share, and either mount the share permanently or use cron to start/stop the mount service when needed, and use cron to run a backup script or whatever rsync command you want for backup (rsync will be quicker than a tar based process).
I'll see if someone on staff fancies a challenge - but it's probably not a high priority. From a quick look the build process pulls in some other packages which is something we don't like in our build system, but it's not an insurmountable problem.
I've taken a mental note to design more white text into the next version (not that I recall there being any in the current)
Kodi v19 is the point we switch from Python2 to Python3.
There's a video for this on our under-used YouTube channel
It's possible to use "autoscript" files to provide uboot with instructions on what to boot (from) but those files do not exist in current 3.14 kernel images and they are compiled scripts (not just plain text files) so there's a little bit of uncharted work involved. If you don't provide instructions uboot will boot from external media if present.
If the slot is "loose" the easier cure is probably to open the case and ensure the connections to the board are soldered properly and the connector tabs that locate the connector housing in the PCB are either tensioned correctly. Or maybe use a hot glue gun to get things under control.
The real credentials are masked with USERNAME:PASSWORD for security reasons as people post logs to pastebin.com and similar.
Spaces in usernames are always a bad idea.
