ok I see this.
How does one then include custom smb.conf setting ?
Read the manual in the Wiki? A lot of time was spent writing it, and there is a wealth of other information there too. Please make use of it and you can then answer this sort of question yourself.
In short, if you set a configuration item manually (and not via the server-manager which only has a subset of configuration items) and run the correct service e-g. console-save or post-upgrade/reboot then the system will re-generate the template for you.
You do not need to do this:
config setprop smb ServerMaxProtocol NT1
expand-template /etc/smb.conf
service smb restart
You should do this or similar:
config setprop smb ServerMaxProtocol NT1
signal-event console-save
If you REALLY need something not allowed by a configuration item ie some new setting (and you need to look in the templates to see what is there, and what is not) then you can create custom template overrides. Read the wiki for more. There are pages on extra settings if required and lots of other good stuff.
Note - Windows will likely outlaw SMB1 before very long - they will pull support entirely and you will have no choice but to use SMB3. It is just a matter of time.
I don't want my shares browsable. I will map them instead.
In that case you seem to have missed the core point that you do NOT need to set it back to NT1 - all that does is allow use of SMB1 on Windows and re-enables NetBIOS browsing.
If you do NOT want browsing then use SMB3 and map the shares. If you use SMB3 and want browsing use wsdd.
What could be possible reasons for not being able to connect to a share/i-bay ?
And that was your original question.
You should have been able to connect because you would be using SMB3. You just could not
browse shares. That is a different thing entirely. Just use SMB3 for your own security, and map the drives.