Hi @tlussnig.
HTTP 400s ( a.k.a. "Bad Request" ) are NOT intended behavior for our ocsp responder URI's - which makes me wonder, what sort of requests are you sending?
The URI "http://r3.o.lencr.org/ocsp" should not actually be a functional URI - as far as I know, that should either return a 404, or maybe "unauthorized". When you say "it works fine", does that mean you're able to POST to this URI and retrieve valid OCSP responses?