Usman Asar

Kelvin,

the code that Rick gave wasn't wrong, this use to work on older moodle default themes, and still will work on some of other than Boost As rick doesn't uses Boost on his moodle, so the CSS didn't work, but he was in correct direction when understanding your requirement. 

anyway, assuming you know where to put the CSS code, try this (you can use either of the Raw initial or Raw SCSS boxes to enter the code)

.sitelink img {display:none;}

anything related to themes, please ask in Themes forum, you would have been helped a lot earlier. 

Craig,

you mentioned 3 nodes of DB server, but 38 sites, how are sites linked? as you as well mentioned case of failure of WAN connection.

Also, when using DFS-R, it wont be just moodledata, but moodle folder as well, unless you're going to copy over moodle folder on all nodes manually after every upgrade/plug-in addition. 

Bernhard, 

First, do try using PHP 7.1, as I think Modole 3.9 is coming with support of PHP 7.2 onwards. 

secondly, Just check your config.php file, if it really is a PHP file and not a text file, for that, you have to turn on file extensions in folder options, and often people do mistake by opening notepad and copying the stuff saving as config.php thinking that its saved as config.php, but in reality its saved as config.php.txt.

third, have you given IUSR permission to moodledata folder? 

Luis, I haven't personally but did gave a thought about it once, considering that third party application may not be stable on server O/S so never tested it, and on top NVMe drives on PCIe 4 bus have similar latency and transfer speeds so waiting on hardware upgrade to test those.