Can't connect to database

[MabelVanA]

I'm not sure this is an appropriate question on this forum, but here goes..
I've been wrestling with this problem for over 8 hours now - so I'm pretty desperate for help.
I have an old-fashioned 'home' setup; with a well functioning (windows10) server running several wordpress sites. Now I want everything to move to a new computer. Trying to avoid any issues with upgrades, I simply:

• installed SQL-server (12) using the same (downloaded) setup-package I used for the current server (default instance, same password) and restored the wordpress database from a backup;
• copied the files in ...\inetpub\wwwroot\MyBlog;
• copied the files in ...\PHP (to a different location, but i adjusted php.in for this)
• added, with IIS manager, a handler for *.php pointing to the new location of the PHP files.
  Finally, I downloadeed and installed the wonderful 'PHP for IIS' applet for IIS-manager which assures me the PHP installation is fine; bringing up phpinfo.php from localhost confirms that (as far as I can see, at least): both the sections 'sqlsrv' and 'pdo_sqlsrv' show up.

And yet my webbrowser confronts me with "Error establishing a database connection".
I'm at a loss here; has anyone any ideas?
Hans
PS: I also verified, by making a DSN, that the local SQL-server can be reached using tcp/ip.

[patrickebates]

Have you confirmed that the TCP port for SQL Server is open? I've seen that a couple of times.

[MabelVanA]

@patrickebates Funy you should say that since I worried about it. For some reason or other the SQL package I used, SQLEXPRWT_x86_ENU.exe, did not contain the sql configuration manager so I can't verify the protocols used directly, but I did successfully make a (working) DSN using tcp/ip as client protocol.
I suppose I could upgrade sql-server to get hold of this 'configuration manager' but so far I've been striving to keep things exactly as they are on my running server right now.
Hans