Judging from inline comments this is a know issue:
// PARAM_URL requires a genuine TLD (I think) This breaks my testing
$temp_wwwroot = clean_param($form->wwwroot, PARAM_URL);
if ($temp_wwwroot !== $form->wwwroot)
I do not think that we need to clean the url that is submitted by amin, because mnet should be IMHO usable in intranets that are using compaly.local or company.lan domains too.