I just get a server error when trying to access /admin, or any other URL. This is a completely new installation on a staging server. The 'Welcome' page shows OK.
I'm guessing this is a .htaccess problem, because if I remove it and change 'omitScriptNameInUrls' to false the login page shows - but unstyled. If I login I get 400 bad request.
I've looked in the web.log, but can't see anything to help there.
The hosting company is IONOS (1&1).