New Mini PC user

Are you trying to use a mobile hotspot (your phone) to keep it online?  I do that out in the field, but if I'm at home in my backyard I like to try to use my home's wifi connection.  You can get a mini monitor to see what's going on with the computer itself if there's some uncertainty.  I got a small screen that is supposed to be used for videographers but it works with anything that has an HDMI connection.  I know there's all sorts of options out there now though.

As far as restarting, I'm assuming you're running Windows now.  Microsoft likes to decide when to install updates and do restarts regardless of what you tell your computer to do with the built-in functionality.  Fortunately someone built a tool to help stop Microsoft from doing this.  It's called Windows Update Blocker by a group called Sordum.  I've just started using this and so far, so good.

I may not be understanding what happened with the mount, but what likely happened is the mount was taking instructions from NINA to track a certain object and then when it lost connection with NINA it just continued on that path, tracking the object until it reached the horizon OR it just stopped tracking entirely when the PC restarted.

So anyway, try to have it set up to remember your home network for a better connection if you can.  I don't think hotspots make sense unless you do not have wifi capabilities where the mount is.  And try that app to prevent restarts.  Assuming the restart was your issue with the mount that should resolve this set of issues.  There's always something new though!

I do not have this model, but an older one, MeLE PCG02 and it works fine for me. The signal is strong enough to connect to it from my laptop via RDP, from a distance of 5-10 meters away (MeLE outside in the garden, the laptop inside in the house). Very rarely I had some disconnections, but nothing serious.
Now, how did you setup your hotspot? On the MeLE or on your phone? I know that Windows by default will not let you setup a hotspot if you do not have an active Internet connection. You need to play a bit with the settings and start the hotspot programmatically.
Another solution which was also suggested here is to make your MeLE connect automatically to your home network. This should be more stable, but of course it will not work when you are out in the field.

I have not had issues when connecting my MeLE to home WIFI and using a remote desktop connection to it.

Regarding the reboots, I prefer to not install third party software to stop it from updating, or disable it in other ways. I like to keep Windows updated to protect from vulnerabilities since it is attached to my home network. To stop the reboots at night, you can go to "Windows update >  Advanced Options > Active Hours", and set that to night time. Then it won't auto reboot during that time period (assuming yours rebooted due to a Windows update).

Hi, 
I am using the same mele quieter 4C fanless mini PC.
regarding your loss of a session it most probably comes from the triggering of an automatic standby mode. I had to track all the parameters of a standard PC of my mele and turn off everything that can trigger a standby of the PC. You also have to track the USB port to remove the option to turn it off to save power. I do not know it by heart but you'll find a lot of ressource on the internet related to it.
regarding the wifi as far as I know there is no way to switch on a PC and have it in access point mode directly. I struggled endlessly to do it. The only way is to start with an existing wifi network declared in the minipc and switch the internal access point later.
To simplify everything, I am using a dedicated hotspot connected in ethernet to the mele 4C and I am using remote desktop to control the mele through this hotspot so the solution is working everywhere even on the field. So I turn on my PC, log on it with RDT from my mac and that's it, it works once setup.
If you decide to control with RDT you most probably go through the well known problem about the way to get access using you classical login giving you access to onedrive. If so there is a solution but I do not have it by heart but I know it exists and where to find it again.

hope this helps, Frédéric

I am currently using this mini PC as well.  I have had some issues using Remote Desktop on my PC.  Sometimes I loose the signal from the mini PC, to my PC in the house.  I am approximately 20 yards from the outside setup, to my PC inside.  I do try to keep the two in line with each other, and that seems to help.  Sometimes it does take a reboot of both systems to get things to settle down.  Sometimes, when I reboot my PC, it reconnects to the mini PC, which has been happily working away!  Cuiv, The Lazy Geek, on YouTube has some good videos on how to set up this mini computer, for using it as an astro computer.  I found them helpful.  I really don't think any of these are perfect, but I am finding that even with some of the problems, it is much easier for me to use this setup, than running 65 foot powered usb cables, out to my rig.  I am not an engineer, but I would have to think, in a world where the is so much RF, that there has to be some interference from all of that, that can mess with the signals.  Check out Cuiv's videos.  He is very helpful.  Clear skies, and good luck!
Mark