m18 R2, can't install apps (unpacking issues) and network connection keeps dropping

Hi
My m18 R2 is having issues where I am struggling to get it set up and stable after a restore.

Firstly, the network connection (wireless) was dropping out frequently only on this machine (other laptops & mac were stable) which is what prompted me to restore the system.

I created a usb SupportAssist stick on another machine to use to restore this m18 (I used the service tag of the alienware to get the right version).

I managed to boot off this, remove existing drive partitions and set it to install Windows. It took several attempts to do this, having 'blu screened' a couple of times.
Once installed I had to set up with a local windows account as it struggled to do it with an existing online microsoft account - it went into a cyclic loop of asking for details, failing after a whilke, then asking again.
 
Once I'd set up the local account I was able to register with the online account.

I then wanted to install Chrome but the setup failed saying that it couldn't uncompress the file.
I tried to do the same with Geforce Experience and I had issues with that, too.

I then downloaded them on another pc and transferred them with a usb stick. Again, the same issues when trying to install.

The network still keeps dropping too while I'm using Edge (I don't have much other software to test with) even though all my other computers/console/TVs/etc. are fine.

Just to add, when I first got the computer several months ago I changed (doubled) the RAM and added a 2nd SSD drive. All was working perfectly.
Because of the issues I've been having I have reverted these changes and put the original RAM back in. I've also swapped the SSDs around and get the same issues whichever drive I try and install to.

Any ideas on what I should do would be most welcome. I'm seemingly getting nowhere just wiping drives and reinstalling the OS.