SMB v1 has been disabled for a reason 
Question was about access to windows smb share.
Yes, SMB v1 is disabled by default in WIN10, but it could be enabled.
Hi Tim,
I’m not very techie and also a newbie to CoreElec so this is going a bit over my head.
I found the sources.xml file, I opened it with Notepad++ but then…I’m not exactly sure where to edit and with what exact syntax.
Would you mind copy/pasting a snippet of your sources.xml file so I can see how and where you edited it?
It’s crazy this has to be so complicated!? Would LibreElec maybe be easier?
Thanks!
Thanks to all who tried to help but this was getting nowhere so I caved in, gave up on the SMB share, setup NFS in my Synology NAS and it seems to be working!
Now I just have several hundreds of Gb to copy onto it! 
I´m only using command line via ssh, no notepad++, but You could do this in KODI/CE
But first You have to enable SMB v1 on Your Windows-PC
Then You have to create a User i.e media with password media and set permissions read/access to Your PC-Share.
After this is done try to connect in KODI/CE
Video - Files - Add videos …
Browse - Zeroconf broser
Add Your share - looks like smb://192.168.x.x:445/myshare and save
If You are asked Username/Password type User/Pass You have created on Your PC
BTW:
It would be the same in LibreELEC.
It´s no rocket science which only could be done by nerds
It´s better to configure NFS on Your CE device in OS - not in KODI
I mount all NFS shares in autostart.sh commands like:
mount -t nfs 192.168.x.x:/ /storage/mnt -o nolock
Just FYI, I have no problems setting up smb shares on a windows 10 computer and then accessing them through Kodi on a coreelec s912 box.
I do (sometimes) have problems if I use the shared computers NAME instead of it’s IP Address.
I do (sometimes) have problems if I use the shared computers NAME instead of it’s IP Address
Interesting! I have only been using the name since I don’t know how and where to get the IP address.
If you could show me, that would be great 
on the windows computer, open a command prompt window (cmd.exe) and enter ipconfig
that should bring up the ip configuration for all the network adapters installed in that particular computer. Look for the ipv4 address for the network adapter the computer is using.
it probably starts with 192.168.x.x This will be the ip address.
alternatively, you could login to your router and see what ip address it is assigning a particular computer or device.
I cant get NFS as per OP.
My fix is to use UPNP.
Working 100%
As far as I am aware UPNP is OK if you don’t want to write to the share. I quite often use “Export Library” to save the xml data and thumbs back to the share. I don’t think this works for uPNP but I could be wrong. Also using uPNP you can’t control who has access to what with network shares if you dont want you kids to access 15 movies you can put them in a share that’s passworded.