This morning my hosting provider has informed me that the url to access isn’t
http://example.com/.well-known/acme-challenge/1fr1GoNRew50h5yemIzdkjaBFAFCmYYkpnIR8yyOE8M.txt
… but
http://example.com/.well-known/acme-challenge/1fr1GoNRew50h5yemIzdkjaBFAFCmYYkpnIR8yyOE8M (without the .txt)
- and all of a sudden there no longer is a problem! The last url does not result in a 404-error, when there is no clear-tag.
Thx for your input, Mushu and rg305!